Potential issue with 'model scope' and 'morphology' field relation

Model has a field named 'model_scope'
Model instance has a field named 'morphology'

Only models with model_scope = "single cell" or "network*" should be allowed to specify 'morphology' field.

Potential problem:
If a user makes a model with, say, model scope = "single cell", and adds a couple of model instances with the morphologies specified. Now if later they edit the model to change model scope to something else (e.g. subcellular).... then what do we do with the existing instances with morphology field.

@apdavison's comment:
It’s not a simple problem. The underlying KG representation is different for the two cases (MEModel vs generic ModelInstance). Probably the simplest way to avoid problems is to disallow changing model scope from “single cell” to anything else.

(Since the scenario may never arise, we could address this later).

Update:
I imagine this to be a more generic problem (not just restricted to 'morphology' field usage), in that model_scope cannot be easily "edited" from any option to another. I think there is a need for more work on this..... disable editing of 'model_scope' completely or something that handles all combos of changes

First map how model_scope and morphology are represented and validated across the MEModel and generic ModelInstance paths. Agree on whether edits are disabled or supported for all model-scope transitions; done is a consistent rule for existing instances and future edits.