What happens if a seller dies after a sale agreement?

Dear Sir/Madam, We(Buyer) bought one acre land year 2002, when we planned for direct registration the seller was died and matter of registration was postponed for an year as both seller and buyer families are close relatives. Since we are close relatives buyer has paid the amount and seller was handed over the old link documents along with passbook. However there was a stay on registration of lands as that piece of land was identified as DOTTED land and subsequently buyer has to wait untill the government suspends the stay on the registration. Now in Andhra Pradesh 2023 government has suspended the stay on dotted land and allowed the people to register the lands. Now the seller has died in 2003 and the heir (wife + 2 sons + 2 daugters) are not agreeing to come forward for registration. So, it has been 21 years that buyer is enjoying the land with out any objection. Seller kids are not coming forward for registration. Thanks