I am buying a resale flat from a person in whose name the porperty is registered by a deed of conveyance and is also mutated in Kolkata Municipal Corporation. The vendor is regularly paying municipal tax. Now the lawyers from the bank (it is being financed by a bank) are asking for death certificate and probate papers and legal heir certificate of very old chain sellers. These documents are imp[ossible for me or the vendor to get. How to resolve this issue?