Documents Needed while Buying a Constructed House

[ramnathgarla]

I am planning to buy a newly constructed house on a BDA site of dimensions 25 * 40 sqft (1000 sqft) in one of the popular localities of Bangalore.
The Owner who is selling the newly constructed house to me, has bought this site (on which newly constructed house was built) in the Year 2011 from a lady who happens to be a Original Allotte of this BDA site. But i also got to know that this lady(Original Allotte of BDA site) was initially allotted a BDA site of dimensions 20* 30 (600 sq ft) and then later was allotted an alternate BDA site of higher dimensions (25 * 40 sqft) by BDA, on which the newly constructed house has been built by the current owner.

So, My concern is How do i verify that the alternate site of higher dimensions allotted to the Orignal Allottee is a Genuine Transaction ?
And what other documents do i have to ask for from the owner so that the newly constructed house that i am planning to buy from the current owner does not have any Legal issues in future ?

Set of Documents that i currently got from the present Owner.

1. Mother Deed
2. Agreement of Sale between the Original Allottee and the present Owner.
3. Sale Deed
4. Encumbrance certificate for the past 10 Years with the name of Present Owner on it.
5. Water Bills and Current Bills for the past 4 Years with the name of the present owner on it.
6. Khata Certificate and Khata Extract issued by BBMP.
7. Builiding Approval Plan


Thanks in Advance.