Validity of will

I came across a under construction flat(80% completed) in Bangalore during my property search. Since the flat is good and comes in my budget I started showing interest and took the documents from builder for legal verification. I need advice on whether to go with this property or not. 2. Person A have bought the land and wrote an will Through which the person B(second son of person A) have acquired the land. *Person A have 7 sons/daughters but the will is written only to second son. No details about property bifercation for other childs. * The will is notarized but not registered. * The will was written in the year 1990 and the person A have died by the year 1993. 3. Person B have transferred the property on his daughter name (Person C) through release Deed. The release Deed is perfect. 4. The person C have gifted a part of land to her husband person D. Land A - owned by person D (husband of person C) Land B - owned by person C (daughter of person B). 5. Person D through join venture, have constructed the flats in Land A which consists of 16 flats. 8 flats will be owned by person D and 8 by builder. 6. As per builders information all these 16 flats is only for sale and none will be used by the landlord for rent\ lease purpose. Already 13 flats are sold. 7. On the neighboring land (Land B) owned by Person C, a flat will be constructed and will be given for rent\ lease. Concrete pillars are raised for 4 floors. Which means that the person C will be owning the land and the building. 8. There is very little space (upto 5feet) between the constructed Land A & B. No wall as of now. But even if the wall is constructed then there will be very few inch gap between the building. I have 2 concerns here, 1. Since the will is not registered will there be any chance of litigation in future? 2. Since the space between the flats constructed in Land A & B is very less, will there be any issue in future? Please Help