Will & asset bifurcation

Dear all, 

 My grandfather has a self earned land property in Tamil Nadu.  My father and uncle are the two sons for him.  My grand father died long time back.  My father is now trying for asset bifurcation between him and his brother (my uncle)  But, my grandfather has written a will saying that all the properties should go to my brother and me.  Along with my father, I also wanted to give equal assets to my uncle.  But, my brother is denying.  The will has been registered.  How to go about it ..for a peace settlement among all of us.  Is there any possibility to make the will null?

Sekar