Property Dispute

Dear Sir, I am facing one of the property dispute and I need your suggestion and help. The background of the property is as follow: My Grandfather has two brother in which from my own grandfather he has two son and his (Grandafter's) brother has three daughter. All are married. My grandfather's brother has died very early and all his property belongs to his wife. Now she (My Grandfater's brother's wife) has written her will to my father, me and my two brother. While the time of writing her will, non of her daughter has raised any objection. The Will was written in 1992 when we were below 18 yrs. And she died in 2008. Now after she died, her all three daughter filed a forgery case and asking for share in all those property which she has given to us. Could you please suggest me, how possible that this will can be broken and court decision will go in their favor? After she wrote Will, my father has given so many money and kind to all her daughter occasionally when they required. But there is no any document proof for that. It seems I am loosing this case. Could you please suggest what to do and how to come up with this situation?