1) if flat is mortgaged to bank ask the borrower to obtain a bank statement about the outstanding loan amount .
2) if flat has been subject matter of loan by means of equitable mortgage then under section 59 of Transfer of property act it does not require registration .
3)however now as per the amendments carried out it is provided that The ‘Mortgage Intimation of Deposit of title deed’ should be physically filed within 30 days from the date of mortgage.
4)you would need bank consent if the borrower wants to create third party rights in respect of the said flat .
5)rather than taking mortgage of flats better give the accused time to make payment in installments
6) you can by mutual consent take adjournments in the case till full payment is made by the accused .
7) as far as MOU is concerned better first obtain bank consent before entering into an MOU . get it drafted by a local lawyer .