Legal Acceptance of a registered sale deed

There is a person call Mr. A who died in 1963 now he's got his son Mr.B who is the only son in the family. this person Mr.B has got 10 children and one of the children which we can call as Mr.C change a part of the property to his name in 1982 after the death of his grandfather however in the legal legal document his grandfather's name has been mentioned in the legal document but his father's name is not mention Mr.C put his grandfather's name in place of his Father's name and inherited the agricultural land now he sold this agricultural land to another person call Me. X and there were also in the sale deed and in the registration he mention his grandfather's name in place of his father however the property is in his own name. The buyer MR.X also died in 1993 and has not disclosed the property to his wife and children and taking advantage of his death, Mr. C has been occupying the said land without informing the family of Mr. X till now. I have to mention that Mr A has got other properties in his name as well which in actual situation has been inherited through his son B and then to his grandchildren now. Now the other brother and sisters of Mr C has file a case in the court saying that the land belongs to all of them and not only to him so the sale document that has been registered should be null and void . Question is how far this sale document is legal ? Can the family of Mr. X file a case of cheating and fraud and compensation over Mr.C.?