Elder brother trying to capture property against grandfathers will

We live in our Grandpa's house. Grandpa past away last year. As per Grandpa's will, my father and uncle are the legal heirs of this house and other properties. Since we are dwelling in this house, my father paid certain amount (fixed by grandpa in will) to uncle for his portion. Now, we r two brothers. My brother and his wife making too much nuisance in this house, forcefully possessed certain portion of this house and land, relation become even worse... My father also too much irritated with them. Now plz advise what realistic legal action my father can take against them, so that my father can live peacefully for the rest of his life... Can my bro claim any part of Grandpa's property in presence of our father...