OMG, I'm sorry, but this is not confusing! No, everything continues as normal in there are any models from the coalition on the board at the end of the game turn. It is exactly as if they were a single player for this purpose.
On that note, I don't care over much, but I think it would be much cooler if one half of the team was allowed to reserve completely. I think the 6th limitations on all-reserve are a little lame, and I think it would be fun to see the old style Descent of Angel lists, or whatever.