Deatails about gpa

Dear Sir/Madam, I am planning to purchase a flat from a seller (register under three parties, Husband, Wife and their Daughter). I have couple of questions. Question (1): The seller lives in abroad. Husband is planning to take GPA of the other two parties (Wife and Daughter) and comes with GPA to India for registration. Is GPA necessarily get it attested in Indian embassy. Is it mandatory to have Indian judicial/revenue stamps on GPA document for attestation at embassy? Question (2): This flat is under mortgage with LICHFL. We (buyer) approached banks SBI and AXIS for loan. (a) SBI representatives said, first the seller must clear the outstanding loan amount with LICHFL then only they will release the loan amount. Before clearing loan dues with LICHFL registration can not be done. Whereas seller is saying unless we pay him, he can not clear the outstanding loan amount. So a deadlock. (b) When we approached AXIS bank representatives, they said, first they will register the flat on my(buyer) name. And, on the day of registration, AXIS bank will handover a cheque to the seller for the outstanding loan amount pending with LICHFL. With that cheque, the seller must clear the outstanding loan amount. After clearing the loan amount, he must submit the documents to AXIS bank (with in a month) then only AXIS bank will release the rest of the amount to the seller. My question is: (a) If we go with SBI, it is not possible to buy the flat as we do not have that much money to pay to the seller without loan. (b) If we go with AXIS, at the time of registration the flat is still under mortgage, how the registration can happen on my(buyer) name? Is this registration valid as the flat is under mortgage at the time of registration? Looking for your advice. Thanks in advance.