How to frag a coral that's growing on rock?

[Steve1500]

I have a bunch of corals (favia, blasto, acans, etc) that I need to frag but they are all growing on rock and I cannot remove the rock from the tank. What is the best way to frag a coral inside the tank that is growing on LR?

I was thinking of using a scalpel to cut a piece around the coral, but not sure how to remove it from the rock itself without killing it.

 

[Fishyfish22]

put something next to it for it to encrust over, wait for it to encrust, and then frag that

most other methods get messy and can break apart the coral