Hi Richard,
As per my understanding, Reference Model's callbacks should be able to handle such situations. In a model hierarchy, the execution of callbacks reflects the order in which the top model and the models it references execute their callbacks. You can leverage this to create variables in your desired order.
Like OpenFcn is a block and model callback. So potentially one could change the Model block, so that if a Model Reference file is specified, the OpenFcn could check if a model is specified and if yes, it could then directly open the mdl file of the referenced model. If no mdl reference is specified it would open the "normal" mask:
Attaching documentation links for your reference
