I have been using a vera light as secondary in my external building for years now and it works flawless and pain free. When I add a device that is in the external building I include it via that secondary controller. The device then automatically populates on the primary. I do all scenes and interaction via the primary after that so that I am not managing things in 2 places. You can add scenes and control only the garage devices from the secondary but I choose to keep it all on the primary and do nothing but add remove devices on the secondary. Primary has access to all devices just as if they were added directly to the primary. It is seamless and you cant tell they are controlled by a secondary controller at all. Interaction with those devices is is 100% as if they were added directly to the primary. (Of/On,scenes, ect)