Are the frags free floating, or are they attached to some sort of substrate or rock? If they are indeed attached to rock or substrate, it should be very easy to attached them with a simple dab of reef safe glue and pressing firmly to a piece of live rock. Make sure the surface are dried with a piece of papaer towel.
If the frags are free flaoting with nothing attached to their surface, just find a piece of rock with a crevice in it. Press the soft frag into the crevice, then wrap a piece of thread between the polyps and around the rock. One loop top to bottom and one loop left to right will secure it. Knot the thread on the underside of the rock. After 10 days to 2 weeks it should be attached and you can remove the thread with scissors or a razor blade. If doing the later, do not place the frag in an extremly strong current as it will prevent it from naturally attaching on its own.
Mucho