Boundaries Mistake(only South Is Wrong Instead Of Plot No. 11 It Is 9)

Hello Sir, My grandfather bought a land in 1990s, on that parent document, in four boundaries one boundary is wrong which plot number 9 instead of 11, after that land came to my father as a partition deed we referred the sub registered and document registered and they asked to correct the boundaries while registering the partition deed, and now my father gave the land to me as a sale deed, the issue is one of the boundary which is plot number 9 instead of 11 which is wrong in parent document but it is correct in the father partition deed and in my sale deed, i am trying to sell the plot but buyer's lawyer is asking to do a rectification deed by asking all the sons of the persons who sold it to my grandfather.