1) you must have entered into development agreement with builder for redevlopment of your land
2) the development agreement must have mentioned 4 flats allotted to you and your family
3)there must not be any sale deed executed by builder in your favour as you are the land owners
4) submit agreement entered by you with the builder for adjudication as to stamp duty payable
5) on basis of adjudication by collector pay stamp duty with penalty if any