With the previous posters I don't feel quite so bad, but I have 3 yellows with a purple, regal, power blue, naso, kole and most recently a sohal. Yes, there is a lot of chaos but all are out and mostly getting along. I have a lot of other fish too and a fairly large tank (350G) so that helps, and I feed a lot.
I didn't have so many when I introduced the three yellows. I really wanted a small school but knew I couldn't add any with the nasty large yellow I had at the time. Also wanted a purple, so I caught the yellow and brought him back to the LFS, and added three smaller yellows and a purple at the same time. I as surprised at how everyone adjusted. I recall I added a small school of anthias too, so even though the system was stressed with so many fish added at the same time, I think it helped diffuse the aggression. I'm pretty much at my max now, although I would love to add a copperband. I have a large one that is eating flakes in QT, but am nervous about introducing him to such a busy tank with what I have read. I know my window isn't large because the fish are starting to settle down into their pecking order after the recent introduction of the sohal.
Andrew