Partition of property

Hi, My great grandfather had 1 son and my grand father has 3 sons. My great grand father and grand father built a house. The utility bills were in the name of my great grand father name who died 20 years back and recently the utility bill transferred in the name of my grand father. The house has not been divided but on recommendation of my grand father my father has shifted to a not so developed or organised part of the house. Now when the family has grown up with adults my father decided to build a room and a bathroom which was agreed by father but when my father started the work in mid way my father's two brothers who are staying in the developed area of the house has started objecting and threatening including showing muscle power. Now my father is facing financial loss as the work has stopped and alot of materials has alreafy been purchased. They have also threatened my grand father if he 'll take a stand in favour of my father. Pkease guide as to how to deal with the situation ot what is the speedy resolution of the problem. Can we file a partition suit so that property will be well divided and then we can carry on the work