Beneficiary's sign on relinquishment deed

Dear Ld Experts, A father died intestate leaving a land property inherited from his father. There are five legal heirs. Wife, three daughters and a son. Wife and three daughters relinquished their share through a single deed of relinquishment to the son in 2013 and got the deed registered. One daughter was not informed that she is going to sign a relinquishment deed. She was called to the registrar's office to sign on an agreed sale deed for part of the property, that was made on the same day together with the relinquishment deed. Recently when she claimed with other co-owners her share in the balance land property she was informed that she has no right over the property since she had already signed on the relinquishment deed. After taking a copy of the relinquishment deed online, it is noticed that the beneficiary has not signed anywhere on the relinquishment deed as other party and not given his thumb impression also. 1) Is this relinquishment deed valid or void from the eyes of law? 2) Is both parties signatures mandatory/legal requirement for validating the relinquishment deed now a days? If so, from when? 3) The original relinquishment deed duly signed by the executants alone and handed over to the beneficiary after registration by the registering officer be considered as a mode of acceptance by the beneficiary? Kindly advise if this relinquishment deed can be challenged. Thanks for your valuable time.