As others have said, the best way to get a good mix, either for a remote room or for recording is with a separate board. It is best if this board is not in a place where the user can hear the live mix. This allows him to mix signals, not a combination of signals and the live audio in the room. Mic inputs can be split and fed to two boards but the splitter and snakes will cost a lot. If you have ever wanted to take advantage of the many features of a digital board, and / or IEMs with individual mixers this may be a good time. Our church upgraded from analog to Software Audio Console board
http://www.softwareaudioconsole.com/ This allowed us to add a second board for recording for the cost of a used PC.
It has worked out great.
Frank