If you add all of them at the same time, this curbs aggression. If they are all relatively the same size, this will most likely do the same thing. If your Naso or any other tang is constantly grazing and being fed, then it's anger should be next to nothing or nothing.
The main problem is them gathering speed and rocking their noggin against a side, a rock or the top of a tank and dying from it. Just one day the tang turns up dead. I wish I knew defining characteristics for "head injury" and fish - but I don't; which I don't even know if there are any. Tank space plays a large factor too. One thing I, MYSELF, found that has helped with tanks with lids, is those little moon lights, just the ones that are seperate that can be plugged into a wall. They sometimes work almost like caution or landing strip lights (then sometimes a fish may try to eat them, LOL).