Mstn has long provided the option for the Active Model to be Ref attached and edited. See setting in the Preferences dialogue. Since V5?

I think the obvious use case would be any symmetrical assembly arrangements: ship hulls, aircraft fuselage/wings, automobile wheel-axles etc.

It would be great to extend this to other local models in the dgn... not just the active model. A check box in the Ref and Model dialogs would be provided to allow the user to select the model(s).

This would reduce the need to exchange into multiple models to edit locally federated models.