1.Before the BDA transferred the allotment to one of the daughters of 'X' i.e., 'G', BDA would have taken 'NOC' from 'X' 's wife and the other children.
2. The sale deed executed by BDA in 2003 in favour of 'G', prior to execution of partition deed in 2007 be considered absolute, in lieu of NOC by other legal heirs. However before arriving at a decision by you whether to enter into a sale agreement or not, one has to study the documents and then decide.
3. In the circumstances detailed by you, the grand children cannot lay claim on the site.