I had a red lip kill a yellow watchman. Literally beat it to death in a day. I had just gotten a new home put up for him and he did not make it. He was small and cute, I was crushed. He (red lip)now lives in 20 long with a 6 line wrasse who is also far more aggressive than I would have thought. They teamed up on the yellow and a firefish. I did get the firefish out in time, luckily he was good at finding hiding spots.
Good luck with your new goodies!!