Grandson rights in ancestral property.

Sir, I have a query about ancestral property partition of my grandfather's property which is acquired by him from his father. Problem is, my grandfather has four sons and right now my grandfather is alive but not my grandmother, and my grandfather wants to do partition of his property among his sons. But the most elder son is not satisfied with ideas of partition. Many proposal were offered to him by family and by other reputed and respected persons of our town but his greed is not letting him agree with any proposal at all. Whenever i or any grandson(all have completed graduation and well educated) tries to talk to him, he refuses to talk to us by saying that "You don't have right to speak with me i am Elder Son of my Father." Actually, he never helped my grandfather in tough life situation and didn't take care of him when needed. My mother and father were always there for my grandfather. But now this is the time of partition he wants more share than any other son. I want to ask you that does any of grandsons have right to speak in front of our Elder Uncle? Do we have any right in our ancestral property? If yes, then do we have equal rights as my grandfather's sons have? Waiting for your reply, Thank You.