Property agreement change & Stamp duty registration

My Father in law (FIL) bought a house in Mumbai i the early 80's, since he was falling short of a small amount he got it from one of his distant cousin. Hence his name was put on the agreement along with my mother in law's (MIL) name, it was also registered and stamp duty was paid. Few years later FIL made the payment and got a transfer deed signed mentioning the loan taken has been made and he (cousin) has no right in the property. This was all done with mutal agreement without any hassel. But, agreement was not changed neither a fresh registration or stamp duty has been done. Old Agreement is only agreement FIL has. He doesn't want any hassel and want the title to be clear for his two daughter to hold the property after him and his wife. How should he go about getting the title on his or wife including 2 daughter's name without approaching the cousin of his? Few points: 1) Hindu Family 2) Both daughter are married and own house under thier respective name. 3) Share certificate hold's name only of MIL. 4) Not in touch with cousin.