Here is a trick you can use to get rid of them on LR
you add to your system.
After/before you cure your LR
( I do it both times) mix a small bucket worth of salt water SUPER salty. I mean off the scale salty. max that puppy out on the hydometer.
Take the LR
chunk, get your tweesers ready, and dunk the rock for a few seconds. pull it out, and any big worms will back half way out of the rock looking for 'good' water. just yank them out. I leave the tiny ones alone, but snag anything that is really big. I have never had it happen to me, but I have heard that mantis shrimp will bail out at this point as well, when they get a taste of that super salty water.
You will not always get all the worm out, which is why I do this before I cure and after I cure the rock. Sometimes you can't get all the worm out, and a chunk gets stuck in there and rots. .... not good for the main tank.
I have one hawk in my tank, he is my bristle worm control fish. Long nose and arc eye hawks seem to like the big ones.