As a back up if the co-host hack degrades with size, Astrid Pruitt taught me a great hack. On the Open Space wall you assign every session a Number for each session in the round. Then have people rename themselves by putting their number in front of their name (i.e 3 NancyWhite). Then the tech host can quickly put people in breakout rooms.?
Then, if someone wants to exercise the law of two feet, they pop out to the main room, and ask to be sent to a new room. We haven't been renaming when people move to a new room/after the round has started.? We have been able to quickly sort quite a few people this way and anyone who gets left off can be easily sorted in once we open the rooms.?
We repeat for the next round. (We did try A1, A2, etc, but that got too messy. Keep it simple with the numbers. )
Nancy White