Incorrect Proportionate Common Area | Deed of declaration vs Sale deed

Hi, We recently purchased a flat and executed the sale deed. We see that there is a mismatch in the deed of declaration (I guess of apartment that mentions all types of areas of all flats) and our sale deed with respect to proportionate common area number. All other numbers like carpet/UDS/SBA/etc are proper. This number could not be crosschecked as it was not present in the sale agreement at the time of booking. The mismatch is coming because builder considers half of terrace area in proportionate common area for all terrace flats in addition to other share of common areas. However, this is not the case for our flat where in, this is missed out leading to lesser ~15sqm proportionate common area. Upon informing the builder, builder is trying to rectify the deed of declaration to match the sale deed. Question 1) How can builder do the above when in reality its the sale deed that needs rectification ? It wont not tally with other flats. We are worried as deed of declaration (apartment level) doesn't need our sign. Question 2) Can sale deed be rectified stating this factual reason ? Thanks