I have seen enough information where it is fairly safe to keep two-queen castles and super them through a queen excluder. How about 3, or even 4 queen castles. Is that a viable option, assuming all three queens were added at the same time and are in a similar stage of development. (3 sisters that just mated). Notice, i am not talking about separated castles in every directions. I am talking about castles that are separated vertically, but over the top the workers can communicate by crossing the excluder. I think it should work fine, but do share your experiences.