Using subassemblies between branches

In my current design, I am using several braches to explore different designs.  I have come across a situation where I would like to use a subassembly from one branch in another branch.   I don't see right away how to do this.  Of course, I would like to merge the final design branch back into the main branch when all is done.

Specifically, I am designing an LED light.  I have several housings designed (in branches) and I have several assemblies using the housings, driver, and PCB assembly.  The LED board assembly was designed in one of the earlier branches. I would like to use the LED assembly in other assemblies in other branches.  

Thanks