the dominant female will likely become a secondary male, but there could conceivably be a battle between all of the females for that dominant slot. how nasty it gets all depends on the fish themselves. if you add more fish, make sure the new additions are smaller than the original fish, and that should take care of the issue.
i had a lone he/she lyretail (she developed a tall dorsal spike and turned pinkish, but i think she stalled in her transformation) for many years that would literally beat the snot out of any other lyretail in the tank, so she remained alone. that being said, she never paid any attention to my chromises.
i currently keep two other species of Anthias (trios in separate setups), and they do the normal pecking order squabbles, but nothing serious.