Daughter not signing in the sale deed

We purchased agricultural land in a village near Halagur in Karnataka from Mr. X in 2018. Before purchasing the property we took legal opinion. The lawyer asked us to go ahead with the purchase. So, we went ahead and purchased the property. Mr. X purchased the land from two brothers in 2011. One brother has 3 daughters and three sons. Father, three sons and and 2 daughters have signed in the sale deed where as one daughter has not signed. The lawyer inspite of charging exorbitantly the fee he didn't inform about it to us. Now when we want to sell the property we came to about this from the prospective buyer's lawyer. When we approached the lady to sign on the confirmation deed in my favour for which we'll pay some nominal amount for her, her husband is demanding Rs. 10,00,000/- for the job. Now when we asked Mr. X how you got the property registered without that lady's signature, he says that she has signed as a witness. But the lady, her husband and brother all are saying that neither she nor her husband were informed about the deal because they were not ready to meet her husband's demands. What do we do now? We feel cheated by the lawyer, our seller who knew about this and didn't inform us, then we would not have gone ahead with the deal. What is the solution for this problem with which we could come out of this with a few thousands of rupees (within Rs. 50,000/- or so)