i would chisel off the mushrooms about half way between them and the
GSP. if you try cutting them there is a chance of slicing the
shroom and killing it. i have never had that much luck at prying them off.
just cut the
GSP that is not attached and either superglue it or rubber band it to the new rock. they are pretty easy to get to grow anywhere. i would also suggest isolating the
GSP so that it can not attach to any other rock in the tank. it WILL overtake anything in its path. i have had it actually KILL an
Acropora colony because it overgrew it and smothered the colony.