‘Cross Project References’ allow for entities to be related to other entities in other projects. 

1. Enter ‘Entity View’ on the entity you want to relate to.
2. Click the dropdown arrow next to ‘Add’ on the relationship you want to use to relate the two entities.
3. Click ‘Relate Existing Entities.’
4. Click the Gear icon next to the entity dropdown menu. 
5. Click or search for the Project that contains the entities you would like to relate to. 
6. Click the entities you want to relate to in the dropdown menu.