Wife wants to become witness for my purchase of land work

respected sir, I want to know whether i can purchase land from my father? we are two brother and three married sister . In 2014 my elder brother died .he had separate kitchen . my father stay with my family. he is now 91 years old after my elder brother died my father want to sell his land and i had purchase that land. now the fact is that my elder brother wife claims her share . can she claim it ? if one of witness is my wife in case of purchase the land is there any problem?