Model Expert Reference Models are just EA packages which contain regular EA content: elements, connectors and diagrams. With a few special tagged-values, but still regular EA things.
So, you can use existing EA features to move Reference Models between repositories.
Baseline them, to keep older versions, restore those baselines, and compare baseline versions
Save the RM package in an other version control tool
Save the RM package in the EA Reusable Asset Server (RAS)
Export them as XMI, and import them into other projects
Print them using tools like eaDocX or the EA RTF generator
Display them in other tools, such as Prolaborate
Replacing Reference Models
When Model Expert links content in your model to a Model Expert Reference Model, it does it using the GUIDs of element & diagram types. So, if you import a Reference Model package and keep the GUIDs, then the imported model will REPLACE the current one.
Creating new Reference Models
If you import it and use the ‘strip GUIDs’ option, then you’ll get a whole new Reference Model, which will not be linked to anything in your repository.