diff --git a/src/bonsai/bonsai/tool/blender.py b/src/bonsai/bonsai/tool/blender.py
index 0c73d58599..40c5059563 100644
--- a/src/bonsai/bonsai/tool/blender.py
+++ b/src/bonsai/bonsai/tool/blender.py
@@ -1328,6 +1328,74 @@ class Blender(bonsai.core.tool.Blender):
         return True
 
     class Modifier:
+        # ----------------------------------------------------------------------
+        # Backward-compat shims for callers still using the pre-refactor API.
+        # The is_<type> predicates now live on tool.Parametric; the Array helper
+        # bag now lives on tool.Array. PR4 migrates each caller; these shims
+        # are removed in PR5's cleanup.
+        # ----------------------------------------------------------------------
+
+        @classmethod
+        def is_door(cls, element: entity_instance) -> bool:
+            return tool.Parametric.is_door(element)
+
+        @classmethod
+        def is_railing(cls, element: entity_instance) -> bool:
+            return tool.Parametric.is_railing(element)
+
+        @classmethod
+        def is_roof(cls, element: entity_instance) -> bool:
+            return tool.Parametric.is_roof(element)
+
+        @classmethod
+        def is_stair(cls, element: entity_instance) -> bool:
+            return tool.Parametric.is_stair(element)
+
+        @classmethod
+        def is_wall(cls, element: entity_instance) -> bool:
+            return tool.Parametric.is_wall(element)
+
+        @classmethod
+        def is_window(cls, element: entity_instance) -> bool:
+            return tool.Parametric.is_window(element)
+
+        class Array:
+            @classmethod
+            def bake_children_transform(cls, parent_element: ifcopenshell.entity_instance, item: int) -> None:
+                tool.Array.bake_children_transform(parent_element, item)
+
+            @classmethod
+            def constrain_children_to_parent(cls, parent_element: ifcopenshell.entity_instance) -> None:
+                tool.Array.constrain_children_to_parent(parent_element)
+
+            @classmethod
+            def get_all_children_objects(cls, parent_element: ifcopenshell.entity_instance) -> list:
+                return tool.Array.get_all_children_objects(parent_element)
+
+            @classmethod
+            def get_all_objects(cls, parent_element: ifcopenshell.entity_instance) -> list:
+                return tool.Array.get_all_objects(parent_element)
+
+            @classmethod
+            def get_children_objects(cls, modifier_data: dict) -> list:
+                return tool.Array.get_children_objects(modifier_data)
+
+            @classmethod
+            def get_modifiers_data(cls, parent_element: ifcopenshell.entity_instance):
+                return tool.Array.get_modifiers_data(parent_element)
+
+            @classmethod
+            def remove_constraints(cls, parent_element: ifcopenshell.entity_instance) -> None:
+                tool.Array.remove_constraints(parent_element)
+
+            @classmethod
+            def set_children_lock_state(
+                cls, parent_element: ifcopenshell.entity_instance, item: int, lock: bool
+            ) -> None:
+                tool.Array.set_children_lock_state(parent_element, item, lock)
+
+        # ----------------------------------------------------------------------
+
         @classmethod
         def try_applying_edit_mode(cls, obj: bpy.types.Object, element: entity_instance) -> bool:
             """Tries to validate the current BIM modifier parameters for the active object