So basically your fragging your coral. Cut them away from the rock they are attached to using a razor. There are a few ways to attach softie frags to a new rock. You could use a tooth pick to pin it to the rock, a rubber band, or super glue gel. If your talking about button polyps or zoos, they are easiest propagated by placing a small rock near the colony and then moving it once they begin to encrust it. You can also break apart the rock they're on. Manually removing and moving them would be tedious, if not close to impossible. That is why polyps, especially zoos, can become a nuissance w/ time if grown on the main rock structure.
HTH