Design Options
Caveat 1: Design Options can be challenging when working with Linked Models. Linked Models are, of course, read-only, and cannot be modified from the Host Model. This means that all Design Options must exist in the Host Model (typically the electrical model for Lighting Professionals).
Caveat 2: When using Design Options, all ElumTools calculations must be done using the Calculate View commands. The other calculation commands will not respect Design Options, and will always only consider the geometry which is defined in the main Design Options. This is due to limitations of the Revit API.
How about Phases?