All my white ringneck young have started feeding themselves and become able to be away from the parents after 30 days, some as early as 23 days. I have never kept them in a cage so small that injuries have happened, so I don't have experience with bully dads.
In the larger fllight cages the young do learn to get out of the way in a hurry, and they can't be cornered by Daddy. So seperate the young and feed them by hand if you have to, you won't be hand feeding for long.