Very old ancestral property - No Mother deed

Hi, This is in regards with the Ancestral property (House) which we are currently living from past 30 years. We were in process of mortgaging the house in bank and the bank people were asking for house related documents. Since it is a very old ancestral property coming from Great- Great fathers and now to my dad. We don't have a mother deed for the document. What all other documents can we show bank instead of mother deed. Below list of documents we have till now. 1) Gift deed registration on my fathers name dated 2006 2) Will deed of my Great grandfather dated 1986 ( telling this house must belong to my grandpa ) 3) House EC past 45 years 4) Property tax from 30 years on my greatgrandfathers name. 5) House mortgaged duplicate copy of my great grandfather in year 1945, 1942 6) Death certificate of GreatGrandPa What all documents can uphold that house is clear for mortgage. Is there any other way to please the bank legal team, they are still urging to bring Mother deed which is not present even in the local Registrar office.