diff --git a/core/nodeslicer/tree.py b/core/nodeslicer/tree.py
index e07a49d..e664f58 100644
--- a/core/nodeslicer/tree.py
+++ b/core/nodeslicer/tree.py
@@ -21,24 +21,40 @@ def get_referenced_objects(node, visited=None):
     visited.add(ptr)
 
     objs = set()
+
+    # Special case: if this is a group node, we must also check nodes inside the group
+    if node.bl_idname == "SLICENODE_Group" and getattr(node, "slicer_tree", None):
+        for internal_node in node.slicer_tree.nodes:
+            objs.update(get_referenced_objects(internal_node, visited))
+
     # Check all input sockets for objects
     for inp in node.inputs:
         # If it's an object socket, it might have a value if not linked
-        if inp.bl_idname == "SLICESOCK_Object":
-             if not inp.is_linked and inp.value:
+        if inp.bl_idname in {"SLICESOCK_Object", "SLICESOCK_ObjectRo"}:
+             if not inp.is_linked and getattr(inp, "value", None):
                  objs.add(inp.value)
         
         # Always follow links to find more objects upstream
         if inp.is_linked:
             for link in inp.links:
+                # Special case: if from_node is CollectionObjects, the object is identified by the socket identifier
+                if link.from_node.bl_idname == "SLICENODE_CollectionObjects":
+                    obj = bpy.data.objects.get(link.from_socket.identifier)
+                    if obj:
+                        objs.add(obj)
+
                 objs.update(get_referenced_objects(link.from_node, visited))
     
     # Also check output sockets of the node itself, 
     # as some nodes might "hold" an object (like InputObject)
     for outp in node.outputs:
-        if outp.bl_idname == "SLICESOCK_Object":
-            if outp.value:
+        if outp.bl_idname in {"SLICESOCK_Object", "SLICESOCK_ObjectRo"}:
+            if getattr(outp, "value", None):
                 objs.add(outp.value)
+            elif node.bl_idname == "SLICENODE_CollectionObjects" and outp.is_linked:
+                obj = bpy.data.objects.get(outp.identifier)
+                if obj:
+                    objs.add(obj)
 
     return objs