BDA should give approval for such DC converted land. It the layout odes not have BDA approvals then the layout will called as unauthorised layouts or illegal layouts. The original Gramathana sites are excluded since they will likely be regularized in the proposed Akrama-Sakrama scheme.
It is not advisable to buy a property that has been approved by Gram Panchayat. I agree that the rate of the property is cheaper as when compared to the area coming within corporation limits, it can be creates a lot of legal problems, in future. It at all you are buying the property check all the documents with the help of legal expert.