Release Deed

Dear Team My father is no more with us after 2001. For his self-earned property (individual house @ Chennai Zone), we total my mother + 3 sons + 4 sisters are legal heirs (8). My mother and sisters are ready to release their rights without consideration. But my brothers are expecting share as per market price. So please advise me on the relinquishment deed & its procedure. Is legal heirship or succession certificate is/are mandatory? Thanking you in advance!