Multiple bank loan property and right of first bid purchaser

Hi, my dad(age 70) purchased a flat under the auction as per sarfesi act. in 2014. from dns bank. now after taking over peaceful possession from dns bank from last six months he started receiving notices in the name of original defaulter fro six different banks. among st them two banks have declared auction and one bank had obtain a order from DM for sealing of property under sarfesi act. now when my dad tried to communicate the officials of dns bank they replied now we are not concerned to you any way in any legal obligations as our role is over on the we have transferred the property on your name.now my question is: 1. can my dad would be removed from the flat if another bank successfully conduct the auction. 2. dns bank is the first bank to give the loan to defaulter. all other banks has disbursed the loan after wards. can this will help my dad somewhere in legal sense fpr claiming clear titile. 3.all banks known that defaulter has obtain loan by mortgaging false and forged documents but none had filed criminal complaint against him. can this point will help me anywhere. what will be legal and lawful remedy to me if all the bank under sarfesi act auctioned the property where my dad is leaving, can any bank disposes my dad and mom from the said property, 4. what are the legal remedies available to my dad so that he cannot be thrown out from his home. is there some guidance judgement from high court or supreme court. please guide