I know this post isent addressed to me but i have plenty of experience fragging mushrooms,zoos,star plyps,galaxea,hammer coral,and kenya tree coral so i think i am qualified
.Take the rock out of the tank(no fragging should be done in the tank unless it is necessary),cut the mushroom off the rock as close to the rock as you can get it.(The Cleaner the cut the faster the healing time).Even take a little peice of the rock if you can.Then once the musrooom is completely off the rock.Slice it completely in half across the oral disc(mouth) into 2 perfect halves.Once again the cleaner the cut the faster the healing time.If you wanna frag one mushroom into four,Cut the halves again across the disc.Once this is done in about 1-2 weeks your mushrooms should be completely healed if done correctly.And in 1-2 months be ready to cut again!Any more questions feel free to ask, there are tons of people out here who can help you