Sarfaesi Act / minor suit

We have bought a property in auction from bank in the Sarfaesi act. The borrower is a lady and the property is her husband's property which was an ancestral property and it has been divided between the brothers by a partition deed in 1997. Now this husband settles his share of property to his wife and she pledges the property in bank and borrows loan and the husband becomes guarantor. Now this loan account becomes NPA and the sarfaesi procedures are initiated by bank after so many warnings. We become a successful bidder after 5 times of auction and we acquire the sale certificate in 2019 and register the same in 2020. Now we have let out the premises for rent to a company and these borrowers send a notice to that company stating that they will file a minor suit ( in favour of their minor daughter represented by the maternal grandmother for claiming share in the same because it was ancestral property) on the above property and they should not execute a lease deed with us. So is this even possible for the borrowers to file a suit on the auctioned property after several excuses and inspite giving time to repay the amount and even after DRAT appeal they failed to remit the 50% amount for the appeal. So please advise on this.