My father passed recently and he leftmy sister as primary be

My father passed recently and he leftmy sister as primary beneficiary of his insurance and my brother as secondary.Well my sister was supposed to pay what bills she had to and then split the rest between all of my fathers children,six to be exact. Things did not go that way and my brother would like to contest her authority and make her step down as executor because she is not going along with our fathers wishes.If he hires a lawyer and has an order for D.N.A done to prove that only two of the six belong to my father and that as biological son he has full right to request everything be turned over into his power,and what money/s she has also be givin so that our fathers wishes be caried out. does this sound like the course of action he should follow,and are his chances of winning any good?