Propagation - fish & corals

Anyone have any tricks to trimming/pruning monti caps that won't look like the bow of a ship smashed through my reef? I've got a lot of purple rim green cap that is out of control and either shading or engulfing some acros that I'd rather not lose. I've already pretty much lost what I would describe as an encrusting/branching rainbow monti.

So I came home after work yesterday to find my perfectly fine bird nest in rtn mode. It's the size of a soccer ball. Today it looks like the progression has slowed or stopped but its probably 50% affected. My fear is that the other corals will get some kind of death signal and follow suit. I'm prepared to break it apart and frag it but that's going to be a lot of frags. So here's a dumb question. Could I glue the frags together to make a new colony of sorts? And should I be looking for some kind ...