Relinquishment deed

dear sir i am very confused what to do.please clarify .my father & mother had purchased a flat flat in joint name.in which my father is first name holder.my father expired 18 months ago.my father has not filled any nomination or will. can we 3 brother make a registered relinquish deed in favor of our mother without producing heirship certificate or it nessesary to produce same.as par bye law no.35 publishing notice in newspaper can chs transfer this flat into my mothers name. please reply.