Selling of ancestral property (land) by my father to servant wife

Sir My father had retired from railway service in july 1994 and settled in village.We are two bothers and settled in Delhi and Varanasi with wife and children from 1995. After the death of mother in 2001, we had keep a servant with his wife and children for look after of my father. in year 2004 my father had distributed ancestral property in block as 7.33 Acres each to both sons and self 2.92 acres, while actual bifurcation was not done as plot no., khata no. etc. on 06.12.2017 my father has expired and it comes to know that my father has registered a sale deed of 2 plots of total area 21 dismal on dated 14.09.17. The name, sign, age of my father written in registry is wrong. my father was ill since some months, can move, walk with help of 3-4 persons. The plots shown in registry is irrigated while residential. The landmark of one plot given is totally wrong. my query is 1. can father sold ancestral property at age of 82 years without consent of successors. 2. The need given in the registry is wrong. we both bothers are Govt. officers, my father was also getting pension of Rs. 30000 per month. 3.My father has written a statement in 2013 that, he will not sell and gift the plots to any person, and after death this will be divided equally. 4. It seems that my father was not in sound mind as name , sign, dob was totally wrong and somebody dictate him to do so. with regards S R Singh