What should be done in case elder brother not signing on partition deed for partition of property?

My name is Sandeep and my father's name is Anand Kumar. They are 3 brothers and 4 sisters. My father is younger one of all the siblings. The house in which we are residing is shared (unequally) by my father and my uncle (next to my father). The house has a shop on the ground floor completely occupied by elder uncle and the first floor (half of which is occupied by elder uncle) in this way we are living in 1/4th of the house and the rest is occupied by my elder uncle. The eldest of these 3 brothers is living separately in his own property from the time when my grandfather was alive. Before my grandfather died he wrote the registry of the house in name of my father and my elder uncle only. Now after his death the eldest uncle is claiming his share in the ancestral house declaring that registry as invalid and in this act my elder uncle is supporting him and asking for 3 equal partitions of the house. Now my question is 1. Do my eldest uncle has the legal right to get a share of the ancestral property? 2. If my elder uncle is not agreeing for the partition what should we do to get equal share in the house?