Newb here, so be gentle. I have reverse engineered multiple physical models. I want to combine all entities into one model, then from there create multiple workspaces. The reason this is necessary is that the models come from sql server databases that have cross database chaining and the entities relate to eachother.
open two of your revese engineered models. Click File | Sync & Convert | Sync & Convert Wizard and use option Merge Models.
In the wizard in step "Select Items" you can see a list of diffeences. Right click your model name and choose Check All Children to Add to make sure that objects that exist in one model will be added to the other one.
In last step you can enable option Merge to New Model. This way you can keep both the original models and create new one.
Continue with other models and after you finish the work, start adding workspaces to the final model.