You're a good portion of the way to figuring it out.

List the things that will be advantages if you include the two new buildings on the master system. Note which ones, like "more flexible control of the music," that would be an advantage but is not likely to be used. Then list the disadvantages, such as whether someone in the cottages could somehow break the main system.

Okay, I don't know elan, but why would the new cottages work any differently? Surely you'll use the same graphics and organization of functions, so it should look the same out there to the existing staff.

I wonder how much the systems will be used if it's mainly for guests. When I stayed at a client's ranch, we were all together watching the movie until it was over, and then we retired to the Hotel. Nothing more than plain old TV was needed there. So think about what people will be doing in the cottages and be as sure as you can be that you're not worried about things that won't be necessary.