diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-lke.json b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-lke.json
index 2ceff9e9..e7ee5185 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-lke.json
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-lke.json
@@ -617,7 +617,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "lakeno": {
+        "lakeno_lakeno2": {
           "type": "record",
           "tagged": false,
           "fields": {
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-lke.toml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-lke.toml
index ec244cf2..32b54d79 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-lke.toml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-lke.toml
@@ -556,17 +556,17 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.flow-ja-face.arms.lakeno]
+[observations.flow-ja-face.arms.lakeno_lakeno2]
 type = "record"
 tagged = false
 
-[observations.flow-ja-face.arms.lakeno.fields.lakeno]
+[observations.flow-ja-face.arms.lakeno_lakeno2.fields.lakeno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.lakeno"
 
-[observations.flow-ja-face.arms.lakeno.fields.lakeno2]
+[observations.flow-ja-face.arms.lakeno_lakeno2.fields.lakeno2]
 type = "integer"
 tagged = false
 index = true
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-lke.yaml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-lke.yaml
index c1dfec06..fc9c0e55 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-lke.yaml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-lke.yaml
@@ -559,7 +559,7 @@ observations:
     type: union
     tagged: false
     arms:
-      lakeno:
+      lakeno_lakeno2:
         type: record
         tagged: false
         fields:
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-mwe.json b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-mwe.json
index b93610b7..68409b7e 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-mwe.json
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-mwe.json
@@ -524,7 +524,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "mawno": {
+        "mawno_iconn": {
           "type": "record",
           "tagged": false,
           "fields": {
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-mwe.toml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-mwe.toml
index fcf1f3f0..2630bc84 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-mwe.toml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-mwe.toml
@@ -469,17 +469,17 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.mwe.arms.mawno]
+[observations.mwe.arms.mawno_iconn]
 type = "record"
 tagged = false
 
-[observations.mwe.arms.mawno.fields.mawno]
+[observations.mwe.arms.mawno_iconn.fields.mawno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.mawno"
 
-[observations.mwe.arms.mawno.fields.iconn]
+[observations.mwe.arms.mawno_iconn.fields.iconn]
 type = "integer"
 tagged = false
 index = true
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-mwe.yaml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-mwe.yaml
index 9b4c5ce3..5705a878 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-mwe.yaml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-mwe.yaml
@@ -476,7 +476,7 @@ observations:
     type: union
     tagged: false
     arms:
-      mawno:
+      mawno_iconn:
         type: record
         tagged: false
         fields:
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-sfe.json b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-sfe.json
index bab54a85..7c2df68c 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-sfe.json
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-sfe.json
@@ -653,7 +653,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "rno": {
+        "rno_rno2": {
           "type": "record",
           "tagged": false,
           "fields": {
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-sfe.toml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-sfe.toml
index b2a75ac2..56978756 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-sfe.toml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-sfe.toml
@@ -590,17 +590,17 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.flow-ja-face.arms.rno]
+[observations.flow-ja-face.arms.rno_rno2]
 type = "record"
 tagged = false
 
-[observations.flow-ja-face.arms.rno.fields.rno]
+[observations.flow-ja-face.arms.rno_rno2.fields.rno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.rno"
 
-[observations.flow-ja-face.arms.rno.fields.rno2]
+[observations.flow-ja-face.arms.rno_rno2.fields.rno2]
 type = "integer"
 tagged = false
 index = true
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-sfe.yaml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-sfe.yaml
index b7151809..1ce54575 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-sfe.yaml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-sfe.yaml
@@ -587,7 +587,7 @@ observations:
     type: union
     tagged: false
     arms:
-      rno:
+      rno_rno2:
         type: record
         tagged: false
         fields:
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-uze.json b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-uze.json
index 24d81d17..7b891c1e 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-uze.json
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-uze.json
@@ -539,7 +539,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "uzfno": {
+        "uzfno_uzfno2": {
           "type": "record",
           "tagged": false,
           "fields": {
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-uze.toml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-uze.toml
index a7098c70..34ba1b3a 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-uze.toml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-uze.toml
@@ -480,17 +480,17 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.flow-ja-face.arms.uzfno]
+[observations.flow-ja-face.arms.uzfno_uzfno2]
 type = "record"
 tagged = false
 
-[observations.flow-ja-face.arms.uzfno.fields.uzfno]
+[observations.flow-ja-face.arms.uzfno_uzfno2.fields.uzfno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.uzfno"
 
-[observations.flow-ja-face.arms.uzfno.fields.uzfno2]
+[observations.flow-ja-face.arms.uzfno_uzfno2.fields.uzfno2]
 type = "integer"
 tagged = false
 index = true
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-uze.yaml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-uze.yaml
index 89967deb..eb76a1b4 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-uze.yaml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwe-uze.yaml
@@ -489,7 +489,7 @@ observations:
     type: union
     tagged: false
     arms:
-      uzfno:
+      uzfno_uzfno2:
         type: record
         tagged: false
         fields:
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-lak.json b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-lak.json
index f6652ae0..604b8179 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-lak.json
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-lak.json
@@ -988,7 +988,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "ifno": {
+        "ifno_iconn": {
           "type": "record",
           "tagged": false,
           "fields": {
@@ -1005,6 +1005,22 @@
             }
           }
         },
+        "ifno_boundname": {
+          "type": "record",
+          "tagged": false,
+          "fields": {
+            "ifno": {
+              "type": "integer",
+              "tagged": false,
+              "index": true,
+              "fk": "packagedata.ifno"
+            },
+            "boundname": {
+              "type": "string",
+              "tagged": false
+            }
+          }
+        },
         "boundname": {
           "type": "string",
           "tagged": false
@@ -1015,7 +1031,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "ifno": {
+        "ifno_iconn": {
           "type": "record",
           "tagged": false,
           "fields": {
@@ -1032,6 +1048,22 @@
             }
           }
         },
+        "ifno_boundname": {
+          "type": "record",
+          "tagged": false,
+          "fields": {
+            "ifno": {
+              "type": "integer",
+              "tagged": false,
+              "index": true,
+              "fk": "packagedata.ifno"
+            },
+            "boundname": {
+              "type": "string",
+              "tagged": false
+            }
+          }
+        },
         "boundname": {
           "type": "string",
           "tagged": false
@@ -1042,7 +1074,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "ifno": {
+        "ifno_iconn": {
           "type": "record",
           "tagged": false,
           "fields": {
@@ -1059,6 +1091,22 @@
             }
           }
         },
+        "ifno_boundname": {
+          "type": "record",
+          "tagged": false,
+          "fields": {
+            "ifno": {
+              "type": "integer",
+              "tagged": false,
+              "index": true,
+              "fk": "packagedata.ifno"
+            },
+            "boundname": {
+              "type": "string",
+              "tagged": false
+            }
+          }
+        },
         "boundname": {
           "type": "string",
           "tagged": false
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-lak.toml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-lak.toml
index abfb46bb..d8fbda81 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-lak.toml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-lak.toml
@@ -877,21 +877,35 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.lak.arms.ifno]
+[observations.lak.arms.ifno_iconn]
 type = "record"
 tagged = false
 
-[observations.lak.arms.ifno.fields.ifno]
+[observations.lak.arms.ifno_iconn.fields.ifno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.ifno"
 
-[observations.lak.arms.ifno.fields.iconn]
+[observations.lak.arms.ifno_iconn.fields.iconn]
 type = "integer"
 tagged = false
 index = true
 
+[observations.lak.arms.ifno_boundname]
+type = "record"
+tagged = false
+
+[observations.lak.arms.ifno_boundname.fields.ifno]
+type = "integer"
+tagged = false
+index = true
+fk = "packagedata.ifno"
+
+[observations.lak.arms.ifno_boundname.fields.boundname]
+type = "string"
+tagged = false
+
 [observations.lak.arms.boundname]
 type = "string"
 tagged = false
@@ -900,21 +914,35 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.wetted-area.arms.ifno]
+[observations.wetted-area.arms.ifno_iconn]
 type = "record"
 tagged = false
 
-[observations.wetted-area.arms.ifno.fields.ifno]
+[observations.wetted-area.arms.ifno_iconn.fields.ifno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.ifno"
 
-[observations.wetted-area.arms.ifno.fields.iconn]
+[observations.wetted-area.arms.ifno_iconn.fields.iconn]
 type = "integer"
 tagged = false
 index = true
 
+[observations.wetted-area.arms.ifno_boundname]
+type = "record"
+tagged = false
+
+[observations.wetted-area.arms.ifno_boundname.fields.ifno]
+type = "integer"
+tagged = false
+index = true
+fk = "packagedata.ifno"
+
+[observations.wetted-area.arms.ifno_boundname.fields.boundname]
+type = "string"
+tagged = false
+
 [observations.wetted-area.arms.boundname]
 type = "string"
 tagged = false
@@ -923,20 +951,34 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.conductance.arms.ifno]
+[observations.conductance.arms.ifno_iconn]
 type = "record"
 tagged = false
 
-[observations.conductance.arms.ifno.fields.ifno]
+[observations.conductance.arms.ifno_iconn.fields.ifno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.ifno"
 
-[observations.conductance.arms.ifno.fields.iconn]
+[observations.conductance.arms.ifno_iconn.fields.iconn]
+type = "integer"
+tagged = false
+index = true
+
+[observations.conductance.arms.ifno_boundname]
+type = "record"
+tagged = false
+
+[observations.conductance.arms.ifno_boundname.fields.ifno]
 type = "integer"
 tagged = false
 index = true
+fk = "packagedata.ifno"
+
+[observations.conductance.arms.ifno_boundname.fields.boundname]
+type = "string"
+tagged = false
 
 [observations.conductance.arms.boundname]
 type = "string"
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-lak.yaml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-lak.yaml
index 700388ab..f89b50a0 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-lak.yaml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-lak.yaml
@@ -997,7 +997,7 @@ observations:
     type: union
     tagged: false
     arms:
-      ifno:
+      ifno_iconn:
         type: record
         tagged: false
         fields:
@@ -1010,6 +1010,18 @@ observations:
             type: integer
             tagged: false
             index: true
+      ifno_boundname:
+        type: record
+        tagged: false
+        fields:
+          ifno:
+            type: integer
+            tagged: false
+            index: true
+            fk: packagedata.ifno
+          boundname:
+            type: string
+            tagged: false
       boundname:
         type: string
         tagged: false
@@ -1017,7 +1029,7 @@ observations:
     type: union
     tagged: false
     arms:
-      ifno:
+      ifno_iconn:
         type: record
         tagged: false
         fields:
@@ -1030,6 +1042,18 @@ observations:
             type: integer
             tagged: false
             index: true
+      ifno_boundname:
+        type: record
+        tagged: false
+        fields:
+          ifno:
+            type: integer
+            tagged: false
+            index: true
+            fk: packagedata.ifno
+          boundname:
+            type: string
+            tagged: false
       boundname:
         type: string
         tagged: false
@@ -1037,7 +1061,7 @@ observations:
     type: union
     tagged: false
     arms:
-      ifno:
+      ifno_iconn:
         type: record
         tagged: false
         fields:
@@ -1050,6 +1074,18 @@ observations:
             type: integer
             tagged: false
             index: true
+      ifno_boundname:
+        type: record
+        tagged: false
+        fields:
+          ifno:
+            type: integer
+            tagged: false
+            index: true
+            fk: packagedata.ifno
+          boundname:
+            type: string
+            tagged: false
       boundname:
         type: string
         tagged: false
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-maw.json b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-maw.json
index 4887333c..516ae38e 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-maw.json
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-maw.json
@@ -654,7 +654,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "ifno": {
+        "ifno_icon": {
           "type": "record",
           "tagged": false,
           "fields": {
@@ -671,6 +671,22 @@
             }
           }
         },
+        "ifno_boundname": {
+          "type": "record",
+          "tagged": false,
+          "fields": {
+            "ifno": {
+              "type": "integer",
+              "tagged": false,
+              "index": true,
+              "fk": "packagedata.ifno"
+            },
+            "boundname": {
+              "type": "string",
+              "tagged": false
+            }
+          }
+        },
         "boundname": {
           "type": "string",
           "tagged": false
@@ -681,7 +697,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "ifno": {
+        "ifno_icon": {
           "type": "record",
           "tagged": false,
           "fields": {
@@ -698,6 +714,22 @@
             }
           }
         },
+        "ifno_boundname": {
+          "type": "record",
+          "tagged": false,
+          "fields": {
+            "ifno": {
+              "type": "integer",
+              "tagged": false,
+              "index": true,
+              "fk": "packagedata.ifno"
+            },
+            "boundname": {
+              "type": "string",
+              "tagged": false
+            }
+          }
+        },
         "boundname": {
           "type": "string",
           "tagged": false
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-maw.toml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-maw.toml
index e98cf307..a0a0854f 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-maw.toml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-maw.toml
@@ -581,21 +581,35 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.maw.arms.ifno]
+[observations.maw.arms.ifno_icon]
 type = "record"
 tagged = false
 
-[observations.maw.arms.ifno.fields.ifno]
+[observations.maw.arms.ifno_icon.fields.ifno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.ifno"
 
-[observations.maw.arms.ifno.fields.icon]
+[observations.maw.arms.ifno_icon.fields.icon]
 type = "integer"
 tagged = false
 index = true
 
+[observations.maw.arms.ifno_boundname]
+type = "record"
+tagged = false
+
+[observations.maw.arms.ifno_boundname.fields.ifno]
+type = "integer"
+tagged = false
+index = true
+fk = "packagedata.ifno"
+
+[observations.maw.arms.ifno_boundname.fields.boundname]
+type = "string"
+tagged = false
+
 [observations.maw.arms.boundname]
 type = "string"
 tagged = false
@@ -604,21 +618,35 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.conductance.arms.ifno]
+[observations.conductance.arms.ifno_icon]
 type = "record"
 tagged = false
 
-[observations.conductance.arms.ifno.fields.ifno]
+[observations.conductance.arms.ifno_icon.fields.ifno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.ifno"
 
-[observations.conductance.arms.ifno.fields.icon]
+[observations.conductance.arms.ifno_icon.fields.icon]
 type = "integer"
 tagged = false
 index = true
 
+[observations.conductance.arms.ifno_boundname]
+type = "record"
+tagged = false
+
+[observations.conductance.arms.ifno_boundname.fields.ifno]
+type = "integer"
+tagged = false
+index = true
+fk = "packagedata.ifno"
+
+[observations.conductance.arms.ifno_boundname.fields.boundname]
+type = "string"
+tagged = false
+
 [observations.conductance.arms.boundname]
 type = "string"
 tagged = false
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-maw.yaml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-maw.yaml
index a5530c6a..8327d921 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-maw.yaml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwf-maw.yaml
@@ -693,7 +693,7 @@ observations:
     type: union
     tagged: false
     arms:
-      ifno:
+      ifno_icon:
         type: record
         tagged: false
         fields:
@@ -706,6 +706,18 @@ observations:
             type: integer
             tagged: false
             index: true
+      ifno_boundname:
+        type: record
+        tagged: false
+        fields:
+          ifno:
+            type: integer
+            tagged: false
+            index: true
+            fk: packagedata.ifno
+          boundname:
+            type: string
+            tagged: false
       boundname:
         type: string
         tagged: false
@@ -713,7 +725,7 @@ observations:
     type: union
     tagged: false
     arms:
-      ifno:
+      ifno_icon:
         type: record
         tagged: false
         fields:
@@ -726,6 +738,18 @@ observations:
             type: integer
             tagged: false
             index: true
+      ifno_boundname:
+        type: record
+        tagged: false
+        fields:
+          ifno:
+            type: integer
+            tagged: false
+            index: true
+            fk: packagedata.ifno
+          boundname:
+            type: string
+            tagged: false
       boundname:
         type: string
         tagged: false
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-lkt.json b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-lkt.json
index d5639ae1..399f85dc 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-lkt.json
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-lkt.json
@@ -569,7 +569,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "ifno": {
+        "ifno_ifno2": {
           "type": "record",
           "tagged": false,
           "fields": {
@@ -612,7 +612,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "ifno": {
+        "ifno_iconn": {
           "type": "record",
           "tagged": false,
           "fields": {
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-lkt.toml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-lkt.toml
index ef3bfcaf..f8eae05f 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-lkt.toml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-lkt.toml
@@ -510,17 +510,17 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.flow-ja-face.arms.ifno]
+[observations.flow-ja-face.arms.ifno_ifno2]
 type = "record"
 tagged = false
 
-[observations.flow-ja-face.arms.ifno.fields.ifno]
+[observations.flow-ja-face.arms.ifno_ifno2.fields.ifno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.ifno"
 
-[observations.flow-ja-face.arms.ifno.fields.ifno2]
+[observations.flow-ja-face.arms.ifno_ifno2.fields.ifno2]
 type = "integer"
 tagged = false
 index = true
@@ -547,17 +547,17 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.lkt.arms.ifno]
+[observations.lkt.arms.ifno_iconn]
 type = "record"
 tagged = false
 
-[observations.lkt.arms.ifno.fields.ifno]
+[observations.lkt.arms.ifno_iconn.fields.ifno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.ifno"
 
-[observations.lkt.arms.ifno.fields.iconn]
+[observations.lkt.arms.ifno_iconn.fields.iconn]
 type = "integer"
 tagged = false
 index = true
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-lkt.yaml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-lkt.yaml
index 22234cf0..0db017ee 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-lkt.yaml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-lkt.yaml
@@ -520,7 +520,7 @@ observations:
     type: union
     tagged: false
     arms:
-      ifno:
+      ifno_ifno2:
         type: record
         tagged: false
         fields:
@@ -552,7 +552,7 @@ observations:
     type: union
     tagged: false
     arms:
-      ifno:
+      ifno_iconn:
         type: record
         tagged: false
         fields:
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-mwt.json b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-mwt.json
index cac1109a..1ccbeee5 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-mwt.json
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-mwt.json
@@ -492,7 +492,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "ifno": {
+        "ifno_iconn": {
           "type": "record",
           "tagged": false,
           "fields": {
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-mwt.toml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-mwt.toml
index 30f57e91..1c4c71f5 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-mwt.toml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-mwt.toml
@@ -437,17 +437,17 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.mwt.arms.ifno]
+[observations.mwt.arms.ifno_iconn]
 type = "record"
 tagged = false
 
-[observations.mwt.arms.ifno.fields.ifno]
+[observations.mwt.arms.ifno_iconn.fields.ifno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.ifno"
 
-[observations.mwt.arms.ifno.fields.iconn]
+[observations.mwt.arms.ifno_iconn.fields.iconn]
 type = "integer"
 tagged = false
 index = true
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-mwt.yaml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-mwt.yaml
index 9dc45235..e12249f7 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-mwt.yaml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-mwt.yaml
@@ -448,7 +448,7 @@ observations:
     type: union
     tagged: false
     arms:
-      ifno:
+      ifno_iconn:
         type: record
         tagged: false
         fields:
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-sft.json b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-sft.json
index 27ae0cda..6298a71e 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-sft.json
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-sft.json
@@ -605,7 +605,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "ifno": {
+        "ifno_ifno2": {
           "type": "record",
           "tagged": false,
           "fields": {
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-sft.toml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-sft.toml
index 88f51c3f..8d16d771 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-sft.toml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-sft.toml
@@ -544,17 +544,17 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.flow-ja-face.arms.ifno]
+[observations.flow-ja-face.arms.ifno_ifno2]
 type = "record"
 tagged = false
 
-[observations.flow-ja-face.arms.ifno.fields.ifno]
+[observations.flow-ja-face.arms.ifno_ifno2.fields.ifno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.ifno"
 
-[observations.flow-ja-face.arms.ifno.fields.ifno2]
+[observations.flow-ja-face.arms.ifno_ifno2.fields.ifno2]
 type = "integer"
 tagged = false
 index = true
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-sft.yaml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-sft.yaml
index da0a3838..3a121df1 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-sft.yaml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-sft.yaml
@@ -546,7 +546,7 @@ observations:
     type: union
     tagged: false
     arms:
-      ifno:
+      ifno_ifno2:
         type: record
         tagged: false
         fields:
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-uzt.json b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-uzt.json
index 3814e241..0b77ae35 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-uzt.json
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-uzt.json
@@ -523,7 +523,7 @@
       "type": "union",
       "tagged": false,
       "arms": {
-        "ifno": {
+        "ifno_ifno2": {
           "type": "record",
           "tagged": false,
           "fields": {
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-uzt.toml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-uzt.toml
index a4bbf49c..f6ec048d 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-uzt.toml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-uzt.toml
@@ -466,17 +466,17 @@ tagged = false
 type = "union"
 tagged = false
 
-[observations.flow-ja-face.arms.ifno]
+[observations.flow-ja-face.arms.ifno_ifno2]
 type = "record"
 tagged = false
 
-[observations.flow-ja-face.arms.ifno.fields.ifno]
+[observations.flow-ja-face.arms.ifno_ifno2.fields.ifno]
 type = "integer"
 tagged = false
 index = true
 fk = "packagedata.ifno"
 
-[observations.flow-ja-face.arms.ifno.fields.ifno2]
+[observations.flow-ja-face.arms.ifno_ifno2.fields.ifno2]
 type = "integer"
 tagged = false
 index = true
diff --git a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-uzt.yaml b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-uzt.yaml
index 94f251f8..872efed3 100644
--- a/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-uzt.yaml
+++ b/autotest/dfns/__snapshots__/v2.0.0.dev3/gwt-uzt.yaml
@@ -478,7 +478,7 @@ observations:
     type: union
     tagged: false
     arms:
-      ifno:
+      ifno_ifno2:
         type: record
         tagged: false
         fields:
diff --git a/autotest/dfns/test_migrate.py b/autotest/dfns/test_migrate.py
index e494809f..7ffaa542 100644
--- a/autotest/dfns/test_migrate.py
+++ b/autotest/dfns/test_migrate.py
@@ -425,8 +425,28 @@ def _obs_forms(field) -> list[tuple]:
             [(("index", "packagedata.ifno"), ("double", "depth")), (_NAME, ("double", "depth"))],
         ),
         ("gwf-uzf", "uzet", [(("index", "packagedata.ifno"),), (_NAME,)]),
-        # a connection number follows a lake number, but not a boundname
-        ("gwf-lak", "lak", [(("index", "packagedata.ifno"), ("index", None)), (_NAME,)]),
+        # a connection number or a boundname follows a lake/well number,
+        # but nothing follows a boundname
+        (
+            "gwf-lak",
+            "lak",
+            [
+                (("index", "packagedata.ifno"), ("index", None)),
+                (("index", "packagedata.ifno"), _NAME),
+                (_NAME,),
+            ],
+        ),
+        (
+            "gwf-maw",
+            "conductance",
+            [
+                (("index", "packagedata.ifno"), ("index", None)),
+                (("index", "packagedata.ifno"), _NAME),
+                (_NAME,),
+            ],
+        ),
+        # APT packages read id2 as a number only
+        ("gwt-lkt", "lkt", [(("index", "packagedata.ifno"), ("index", None)), (_NAME,)]),
         ("gwf-lak", "outlet", [(("index", "outlets.outletno"),), (_NAME,)]),
         (
             "gwt-lkt",
diff --git a/modflow_devtools/dfns/observations.py b/modflow_devtools/dfns/observations.py
index 864944f3..c490d98e 100644
--- a/modflow_devtools/dfns/observations.py
+++ b/modflow_devtools/dfns/observations.py
@@ -24,9 +24,13 @@ def _cellid(name: str = "cellid") -> v2.Array:
     )
 
 
-def _record(*fields: "v2.Integer | v2.Double | v2.Array | v2.Union") -> v2.Record:
-    """ID and ID2, named after the first."""
-    return v2.Record(name=fields[0].name, tagged=False, fields={f.name: f for f in fields})
+def _record(
+    *fields: "v2.Integer | v2.Double | v2.String | v2.Array | v2.Union",
+) -> v2.Record:
+    """ID and ID2, named after both (e.g. ``ifno_iconn``) so records that are
+    arms of the same union get distinct names."""
+    name = "_".join(f.name for f in fields)
+    return v2.Record(name=name, tagged=False, fields={f.name: f for f in fields})
 
 
 def _or_boundname(form: "v2.Integer | v2.Array | v2.Record") -> v2.Union:
@@ -55,6 +59,16 @@ def _connection(pk: str, iconn: str = "iconn") -> v2.Union:
     return _or_boundname(_record(_index(pk, fk=f"packagedata.{pk}"), _index(iconn)))
 
 
+def _connection_or_name(pk: str, iconn: str = "iconn") -> v2.Union:
+    """A feature and one of its connections, or a boundname for all of them,
+    after a feature number or not (MF6 then ignores the number). LAK and MAW
+    read a boundname as ID2; the APT packages read ID2 as a number only."""
+    feature = _index(pk, fk=f"packagedata.{pk}")
+    boundname = v2.String(name="boundname", tagged=False)
+    arms = (_record(feature, _index(iconn)), _record(feature, boundname), boundname)
+    return v2.Union(name=pk, tagged=False, arms={arm.name: arm for arm in arms})
+
+
 # Stress packages
 _CHD = _all(_CELL_OR_NAME, "chd")
 _WEL = _all(_CELL_OR_NAME, "wel", "to-mvr", "wel-reduction")
@@ -157,7 +171,7 @@ def _model(*depvars: str) -> dict[str, _Field]:
         "volume",
         "surface-area",
     ),
-    **_all(_connection("ifno"), "lak", "wetted-area", "conductance"),
+    **_all(_connection_or_name("ifno"), "lak", "wetted-area", "conductance"),
     **_all(_LAK_OUTLET, "ext-outflow", "to-mvr", "outlet"),
 }
 _MAW = {
@@ -173,7 +187,7 @@ def _model(*depvars: str) -> dict[str, _Field]:
         "constant",
         "fw-conductance",
     ),
-    **_all(_connection("ifno", "icon"), "maw", "conductance"),
+    **_all(_connection_or_name("ifno", "icon"), "maw", "conductance"),
 }
 _SFR = _all(
     _feature("ifno"),