Allotment of new 'A' plot where sale deed and 7/12 extract is done

Agricultural land plot for which sale deed and 7/12 extract is done. Project/land developer wants to move/allocate a different plot now through correction deed. Gat number remains same. The new plot is smaller than old plot by 300 sq ft. Land developer is saying in the correction deed the size will be mentioned as the size of the original plot as it is mentioned in the 7/12 extract. Though the new plot is smaller than the old plot. Can we do it this way? What implication will have at the time of selling the new plot if we go this way? If we can't do it this way, how can we do it, without reregistration? How can we change the 7/12 extract to reflect the correct size of the new plot?