L.C.
I was in the same situation in 2003. If I had to do it all over again I would have asked both of them to find a way to get along for me. Or I would have to replace both of them. Instead I replaced 1 of them and ended up losing a good friend.The one I kept didnt do anything she was supposed to do anyway. I think picking her over the other made her head swell.
I definately agree with everyone else about getting the 2 of them together with you and tell them either they make nice around wedding prepperations or you'll have to replace them.