Perhaps I am confused by the iOS 11 announcement, but I thought my existing 4th Gen Apple TVs would be a compatible multi-room Airplay 2 speaker once I downloaded the IOS and TVOS updates today. As far as I can tell, I can only stream from my IOS device to a single Apple TV at a time even though I have 3 4th Gen Apple TVs hooked up to TVs and sound systems around my house. On demos, speakers show up in Airplay 2 as a speaker icon whereas my apple TVs are showing up as an Apple TV icon. It seems as though you need to add Apple TV as a "speaker" in Homekit, but it's not clear to me how to do that for Apple TV either. Did I not understand how this is supposed to work?