Eviction from our share of property

My grandfather has devided his native house property between my father and grandfather verbally. My uncle built a house in half of the plot and the other half is having our old house. My family with my grandfather moved to city 10 years back, and my uncle and his sons used to stay in that whole property. We allowed them to use my father's share as well. Now when my father is asking to vacate my father's half share of that property (old house), he is not willing to do so. The whole property is still on my grandfather's name and he's ready to help my father in every possible way to get back our share. My grandfather requested my uncle several times, but he is threatening my grandfather and my father. Can you please help me out what legal action we can take? My grandfather is willing to register the whole property (both my uncle and father's share) to my name but I don't want the uncle's part, we only want our share. Please suggest.