Nomination in Post office and Bank

Hi Devajyoti , I have a situation and seeking your guidance: Does nomination in post office or Bank means the nominee can withdraw the entire amount in account or in MIS / FD? Reason why I am asking is : My father has made me nominee in his pension account (Bank account) but for the MIS and FD he made in the post office has my brother as nominee. Can my brother withdraw the entire amount in MIS and FD in post office and deprive me of my share ? Can I legally challenge my share in those MIS and FD ? If yes how ? What is the process ? If my father has voluntarily given some money to my brother from those MIS & FD which were matured in 2021 & early 2022 Can I challenge my share from that amount as I am Legal heir of my father as well ? My father expired on 13th May 2022 . I has never disclosed anything about his savings FD or MIS etc to me . Hence I do not have any clue right now what I will get out of it . We are two brothers , my mother also expired on 3rd July 2014 . No sisters . Please guide. Also please let me know your consultation fees. Thanks , Dhrubajyoti Nath