Regarding MHADA flats

I am a law student. One of my friend come to me and ask a Question which are i m posting for your suggestions. In or between 1997 or 1999 my friend's father has purchased a MHADA flat in MULUND at that time my friend with his family stay in Nanded. My friend doesn't know the address of the flat and before he get mature his father was dead. The problem is at that time my friends uncle entered in house and theft all documents of the flat. After the age of maturity his uncle is asking him to pay 15 lacks for the document and to give him address of the flat. Now my Question is how can i know where the flat is ?. From where and from which authority i get such information. Should i do RTI and ask the MHADA to produce the list and also to Registration office to give information of registration done in that year. Or is there is any another way to get the information about the flat and duplicate copy of documents. Experts plz suggest and do the need full. Thanking you.