If you keep a large enough group, in a very densely planted tank, when a pair breeds, the others will all go into hiding. If they do chase another fish, it won't be sustained, the aggression will be spread around. IOW having 7 is probably better than 3.
If you vac up the eggs, often things will go back to normal. What you don't want is for a pair to form and then NOT lay eggs because they can't find a space. That means they will harass other fish indefinitely. To induce breeding, its good to have flat surface in hidden area.
It might also be possible with cichlids, to have enough dithers, or a really large centerpiece so that they never feel totally secure breeding. That may stop them.
I think a group of seven angels in a 125g would work well. In my 75g, I bought 3 angels, and only 2 tolerate each other. I'm not sure if there is a magic number for a 75g. I'm guessing its too small to keep a group of 7 angels. And 4-5 would probably be subject to some being singled out with aggression.