want share in my grandfathers property, my uncle took it illegally.

3 plots 5 brother Very eldest one died and his family is living in 1 plot. My father is 2 eldest we are living on rent. They are not letting us to to live in the property. We are two brothers and one sister. And father is a alcohilic. He is always drunk.we are in a huge problem. And the three youngest brothers is living in 2 joined plots. How can i get my share?