My neighbor has illegally possessed a part of our shared property and even though he doesn't have a

My neighbor has illegally possessed a part of our shared property and even though he doesn't have a right to build a house there as the property doesn't even belong to him. It belongs to my grand father's brother and after he passed away his family couldn't divide the house among them and so 2 brothers sold the house without transferring the papers and as the person who bought the house was a member of Nagar palika at our place. He abused his power to build the house without even passing the map by a secretariat from nagar palika. And he has taken over a part of shared passage and covered it with a roof over half of passage. Can you please advise if we can go to court with this case and what are the chances of a fair play in court.