This is not supported out of the box.
However, the WroModel expose the merge operation, so you could create an implementation of WroModelFactory which aggregates the results of GroovyModelFactory for different groovy resources and merge them into a single model.
This might be a nice addition. If you are willing to extend the GroovyModelFactory, so that it could accept imports and share your contribution, I will gladly include into the next release.
Cheers,
Alex