I can give you my experience. Over time I've added one angel after another. Adding all at once would probably have been the easiest way to do it. I now have 6.
I started with a coral beauty. My next addition was a bi-color. There was some chasing and the bi-color stayed up towards the top corners. I watched for anything other then chasing up to the corners and ready with a breeder box. But that was it for about a week. The coral beauty has never been aggressive toward the bi-color again. I never had to break out the breeder box.
Next addition was a flame. Again the coral beauty took off after it. But same as before just chased the flame up to the corners. Again, for about a week. Never aggressive towards that flame again.
Then I added a multi-colored. The coral beauty flipped out. Went psycho on it and took a chuck from the dorsal fin. Broke out the breeder box and put the multi-color in for about a week. The multi-color was a good size too and slightly bigger then the coral beauty. The other two were smaller. Maybe that had something to do with it. After a week I did another trial and the coral beauty just chased the multi-color to the corners for about another week.
Revenge.... The multi-color after getting acclimated to the environment and fed well started to chase the coral beauty and do a move to block the coral beauty into caves and do a side ways wiggle like I'm the dominant angel now and I can trap you in there. That lasted aggressively for a couple weeks and rarely happens anymore.
Then I added another flame. The multi-color and coral beauty lost their minds and were both super aggressive and out came the breeder box. One week in, 2nd week back in, 3rd week back in, 4th week back in and finally the 5 week they did a little chasing but not terrible and died down after that.
Now recently I just added a lemon peel. Nothing. The most aggression turned out to be from my bi-color that has ignored the others. Chased the lemon up to the corners for just a day then the lemon pushed back once and that was it.
Now a days there will be a little chasing here and there but it's quick and uneventful and often humorous. One will chase quickly another but then the one being chased will just abruptly stop and flash itself sideways and will end up chasing the chasey quickly.
Periodically the multi-color will do its dominance dance blocking the coral beauty in a cave but that's about it.
My two flames do something else weird. I don't think they are a pair and no idea how to sex any of them. But what is the slightly bigger and seems more dominant flame will run up to the other flame. The other flame will just freeze side ways to it flashing it's dorsal fin but not doing a dominance wiggle. Then the bigger flame looks like it does a quick nip but then both just kind of swim off. I have no idea what that's about.
Can see my five in this video
And pictures of them and now the lemonpeel in my tank thread
The pipe organ still doing ok. I do see the filefish nip at it periodically but doesn't seem to be enough or doing much damage so far.
www.reef2reef.com