Succession certificate

My father expire in last month. he was a government employ. 15 years before my mother & me separated (without divorce) from my father. After separation in 2001 my father married with our neighbour aunty in a temple. they can not registered his marriage because my mother & father have not divorced. Now my fathers office GPF's & all other gratuities are the name of the nominee since 1990. nominees are my mother 50%, me 25% & my fathers elder sister 25%. this nominatiaon in his service book. but officials are not giving us no gpfs & etc. moneys. my fathers second wife has two daughters one 08 year & second 10 years old. so what can be possibilities here for claim. second thing is my fathers has two storey house. in this house my fathers second wife lived in his 02 daughters. her another two storey house on beside of my fathers house. i am the elder heir of my father. my father buy this house in 1994 in the name of himself & my mothers name & i m there's nominee. but once again officials told us they can not mutation (NAMANTARAN) of my mother's name in the house. now please tell me what can we do.