Order 37 received from buyer with false accusations

My property was sold for 60 Lakhs ; during the sale buyer wanted to register the property for lower value to save registration costs and give part of the transaction as cash (BTW, since this property didn't appreciate much in 10 yrs, i had zero capital gain tax). Since I refused to accept cash, the buyer wanted separate accounts to send the money and my parent's account was used for accepting part of the sale consideration. After 2 years now the buyer has sent Court summon using order 37 against my aged parents claiming the money he sent to their accounts was a loan by showing his RTGS slips. I have the original informal sale deed for 60L to defend myself but Since he is using order 37 wisely to falsify the details and committing fraud against the system and a crime against senior citizens, wondering any insights or tips from any to close this matter. Thanks !