Inheritance property

I am going to buy a house and owner of this house has been deceased few years ago. The departed have 04 sons and 01 daughter. 01 son from siblings saying that he is now only the heritor of this house as all others from his siblings are living separately on other places. Heritor saying that he gave some amount to all of his siblings in lieu of this house and he is now the legal heritor of this house since few years. Further he saying that buyer can check from pattwarii and he is only the authority to get faraad from pattwarii's office as he is the legal inheritor of this property in government or pattwarrii's account.
My worry is how do i check/ cross verify the legal position of heritor.
1- how should i know either heritor (one person from siblings) is the right person to deals with?
2- how should i check or cross verify that heritor's other siblings have no objections in future if i deal with one of their brother who is saying that he is heritor.
I shall be very thankfull to you if you answer me and let me in case further queries. Thanks