Edit: I caught a group late last night and we got it done. Here are some tips we found out:

1) Lullaby works very well.
2) Cannot sleep charmed party members.
2) The Ghost NMs can be dragged out of the room and do not teleport.
3) The Ghost NMs can also be slept with lullaby.
4) We ended up clearing the hallway outside the rooms and sneak pulling the NMs out to fight them.

Gonna use this post for anyone who wants to pick up with Promyvion-Vahzl later today.