Coaching Question

[Jim Armstrong]

I just finished my first season, sometimes I really feel like I'm working a great game, other times I still feel like a freakin rookie. I had something happen in my last game, that I hadn't seen yet. The head coach of team A, at the beginning of the second half, sat down, and the Asst. coach got up, and started using the coaching box. I asked my partner if this was ok, and he said it was, as long as both coaches weren't standing up coaching at the same time. Is this correct? Also what if the head coach loses the box due to indirect T's. The box is lost for the game right? The Asst. can't take over the box in that situation, correct?
I don't have my rule book handy, and thought I could get a quick answer from the board. Thanks!