Which coach?

[Judtech]

Been awhile. Here is the question
Does it matter which coach stands, so long as only that one coach is standing? Had a HC who was pregnant and told us prior to the game that she would be sitting but her Assistant Coach would be standing. I said NP, and the standing coach was fine. Had a couple of calls she didn't like and said some things, asked some questions but no big deal.
After the game one of my partners mentioned that he didn't think it was permissible. We actually couldn't find anything in 'The Book' one way or other. Any help? We bet dinner on it, so it's serious!