Navigating land sale disputes

My grandfather has six sisters and one son. Four of them are married, one is divorced, and two are unmarried (age>40). The two unmarried sisters made a fake registration, claiming no son. We have a land, and my dad's two sisters are being forced us to sell it under pressure. We agreed to sell the land, and the buyer gave advance payments to both parties (sisters and son). The land was divided into two parts, and the two sisters are now claiming they didn't receive any advance and are refusing to sell. The buyer has filed a case, and the court has asked him to give a 2% interest to us. However, he is refusing to release the money until the two sisters agree to sell. Now, the two sisters are demanding the entire land and pressuring us to give and leave. The buyer is not giving the remaining money and has appealed to the high court after failing in the local court.