diff --git a/mex/editor/edit/transform.py b/mex/editor/edit/transform.py
index f8d25e5..909fdae 100644
--- a/mex/editor/edit/transform.py
+++ b/mex/editor/edit/transform.py
@@ -159,16 +159,15 @@ def _transform_field_to_subtractive(
     field: EditorField,
     subtractive: AnySubtractiveModel,
 ) -> None:
-    if (field.name in MERGEABLE_FIELDS_BY_CLASS_NAME[subtractive.entityType]) and (
-        (subtracted_values := getattr(subtractive, field.name)) is not None
-    ):
+    """Transform an editor field back to subtractive rule values."""
+    if field.name in MERGEABLE_FIELDS_BY_CLASS_NAME[subtractive.entityType]:
+        subtracted_values = getattr(subtractive, field.name)
+        merged_class_name = ensure_prefix(subtractive.stemType, "Merged")
         for primary_source in field.primary_sources:
-            for value in primary_source.editor_values:
-                if not value.enabled:
+            for editor_value in primary_source.editor_values:
+                if not editor_value.enabled:
                     subtracted_value = _transform_editor_value_to_model_value(
-                        value,
-                        field.name,
-                        ensure_prefix(subtractive.stemType, "Merged"),
+                        editor_value, field.name, merged_class_name
                     )
                     if subtracted_value not in subtracted_values:
                         subtracted_values.append(subtracted_value)
diff --git a/tests/edit/test_transform.py b/tests/edit/test_transform.py
index de3dc9e..5263add 100644
--- a/tests/edit/test_transform.py
+++ b/tests/edit/test_transform.py
@@ -444,9 +444,100 @@ def test_transform_render_value_to_model_type(
     assert model_value == expected
 
 
-def test_transform_field_to_subtractive() -> None:
-    assert _transform_field_to_subtractive()
+@pytest.mark.parametrize(
+    ("field", "expected"),
+    [
+        (
+            EditorField(
+                name="unknownField",
+                primary_sources=[
+                    EditorPrimarySource(
+                        name=EditorValue(text="Primary Source 1"),
+                        identifier=MergedPrimarySourceIdentifier("PrimarySource001"),
+                    )
+                ],
+            ),
+            {},
+        ),
+        (
+            EditorField(
+                name="familyName",
+                primary_sources=[
+                    EditorPrimarySource(
+                        name=EditorValue(text="Primary Source 1"),
+                        identifier=MergedPrimarySourceIdentifier("PrimarySource001"),
+                        editor_values=[
+                            EditorValue(text="active", enabled=True),
+                            EditorValue(text="inactive", enabled=False),
+                        ],
+                    ),
+                    EditorPrimarySource(
+                        name=EditorValue(text="Primary Source 2"),
+                        identifier=MergedPrimarySourceIdentifier("PrimarySource002"),
+                        editor_values=[
+                            EditorValue(text="another inactive", enabled=False),
+                        ],
+                    ),
+                ],
+            ),
+            {"familyName": ["inactive", "another inactive"]},
+        ),
+    ],
+)
+def test_transform_field_to_subtractive(
+    field: EditorField, expected: dict[str, object]
+) -> None:
+    subtractive = SubtractivePerson()
+    _transform_field_to_subtractive(field, subtractive)
+    assert subtractive.model_dump(exclude_defaults=True) == expected
 
 
 def test_transform_fields_to_rule_set() -> None:
-    assert transform_fields_to_rule_set()
+    rule_set_request = transform_fields_to_rule_set(
+        "Person",
+        [
+            EditorField(
+                name="givenName",
+                primary_sources=[
+                    EditorPrimarySource(
+                        name=EditorValue(text="Enabled Primary Source"),
+                        identifier=MergedPrimarySourceIdentifier("PrimarySource001"),
+                    ),
+                    EditorPrimarySource(
+                        name=EditorValue(text="Prevented Primary Source"),
+                        identifier=MergedPrimarySourceIdentifier("PrimarySource002"),
+                        enabled=False,
+                    ),
+                ],
+            ),
+            EditorField(
+                name="familyName",
+                primary_sources=[
+                    EditorPrimarySource(
+                        name=EditorValue(text="Primary Source 1"),
+                        identifier=MergedPrimarySourceIdentifier("PrimarySource001"),
+                        editor_values=[
+                            EditorValue(text="active", enabled=True),
+                            EditorValue(text="inactive", enabled=False),
+                        ],
+                    ),
+                    EditorPrimarySource(
+                        name=EditorValue(text="Primary Source 2"),
+                        identifier=MergedPrimarySourceIdentifier("PrimarySource002"),
+                        editor_values=[
+                            EditorValue(text="another inactive", enabled=False),
+                        ],
+                    ),
+                ],
+            ),
+        ],
+    )
+    assert rule_set_request.entityType == "PersonRuleSetRequest"
+    assert rule_set_request.model_dump(exclude_defaults=True) == {
+        "subtractive": {
+            "familyName": ["inactive", "another inactive"],
+        },
+        "preventive": {
+            "givenName": ["PrimarySource002"],
+        },
+    }