Platys fin nipping Angels

we have a 30 gallon breeder, with 1 African feather fin, 3 angels (1 about 2 inches, 2 1.75) 5 platys (4 male) and 6 Mollies (1 male). I know we have to upgrade the tank (to a 55) soon for the angels.

Today we noticed the Platys fin nipping the Angels, around the same time the African feather fin started chasing the same angel that was being fin nipped. We noticed it happened to another angel.

My question is should I return the platys, get another platy so there is 6 or go ahead and upgrade to the 55 a bit ahead of schedule?

The plant cover is just starting to get really good, there are times when all you'll see in the tank is one angel, so I don't think it is lack of hiding spaces. I am worried it is aggression due to lack of room as everyone grows.

Thank you for any advice!