Can gift deed be challenged after 60 years cancelled or voidable

My father has 4 brothers. A,B,C,D. MY father's grandfather had a property who gifted his 2 grandsons with a registered gift deed in his life TO A and B in the year 1960. And their name were mutated in corporation record in the year 1961. And the donor died in 1961 at age 85.Later C died issueless. now B with mutual compromise transfer his share to A in Court.LATER B died too in the year 2012.Now A become 100%owner of the property. NOW D challenge in court that the deed is fake and the donor never executed any deed in his life time. And the signature made by the donor is also fake becz the donor was a literate person and the the witness in deed is also fake and hired by A. This are the allegation from D. THE matter is in court. Amendment pf the plaint is allowed and D planning for parmanent injunction. my question is 1) is the gift deed voidanle or can be cancelled? 2) is D the chances of getting share on that property? 3) can that injunction be vacated if allowed?