Two options:
1. Filing I-539 to change your status from H4 to F1 first, filing your I485 after getting F1 approval notice. It may take 2-4 months. But if your parents's I485 are approved during this period of time, You will fall into bad situation.
2.Filing I485 immediately and applying EAD (c9 based) at the same time.
So your are able to work.