Hi Wayne,
Give this a read:
http://www.athiel.com/lib5/goniopora2.htm
From what I read on there I would not recommend putting them close together. Seeing that they are hard to keep alive in an aqarium it would be best to keep them away from other corals so that you stand a better chance of survival. I do hope these work out for you as they are a very nice looking coral. I wish you all the best.
P.S. I have some mushrooms in my tank that are spreading like crazy. You are welcome to have a few if you like. If you do want a few just drop me a PM.