Small system of 13 years, but I still add a few corals occasionally more for my interest than anything else.
When corals are growing well, I think it's common that one would have some concerns (especially in a mixed reef if more aggressive coral is present). A couple choices I can think of are keeping only passive type coral, initially spacing corals far apart to buy time, slowing down growth (adjusting lighting schedule, feeding frequency, etc.), placing barriers in between corals , relocating (if possible) or just let the interaction proceed (which is what happens all the time on a natural reef).
IME, only occasionally have I had to resort to drastic measures and actually physically remove a coral completely from the system. Over time many corals will come to a tentative truce after initially doing battle or just grow around each other (avoidance behavior).