I have two tables/forms:  Franchises and MasterFranchises.  Each has a field named Franchise_Name.  The forms are identical except that the Franchise form also has a field for MasterFranchise.  All franchises are "owned" by a master franchise.

 

In some other forms, I have a Franchise field that looks up franchises in the Franchises table.  So far so good.

 

But in some forms, I would like to have a Franchise field whose picklist is a combination of both franchises and master franchises.  Is there any way to combine them dynamically and populate the picklist with the combined list?  (I can't use ui.add as it replaces the existing entries rather than adding to them.)