Transferring of property

Hi.. My Grandfather who had a self acquired property sold it to a third person without the consent of his wife and eight children. Whether it was a sale deed or a gift deed was known. My grandfather died in 2002 and had transferred the property before his death when his wife (i.e. my Grandmother) was alive. Is it possible to transfer the property in such a manner when my Grandmother was still alive and the children were entirely dependent on the father to sustain life. My Grandfather's primary occupation was farming. The eight children consists of four male and four female. However, the third person whom the property was sold has transferred some part of the property through a gift deed to one of the children for probably not showing any rebel in the future. So, out of eight children only one of the children is benefitted. It may be confirmed whether non transfer of the property to the rightful owners (i.e the children) can be challenged in the court. As on date, no records are available with the children with regards to the sale deed, transfer of property etc. I wish to obtain the same under RTI to file a case before the Court of Law. What actions are required to initiated. Please help.