Every fish is different. I have 2 really good females that leave their fry alone. But i have run into my beautiful blue girl that eats all her fry. She was just rejected from my breeding program as of yesterday. She just went into my "sell " tank.
My platies in there never touch any of them. They chase a little but never persue. They are really good with my rcs too. As long as your tank is heavily planted you should have no problems.