The buildings are only 50 feet apart. When you say "bridging" -- is this just a natural side effect or is some thing else required? There may even be some electrical wires from B1 that are only 10 feet or so from B2.
If no modifications/hardware are required, I guess I just plug/install some device in B2 and see if the ISY picks it up?
Michael, thanks for the tip on the admin page.