We have a house which my grandfather built and in front of the house we had a huge land as well. My grandfather has 3 sons and we all lived in that house as a joint family. The house has 2 floors, in one floor two families stayed and in the top floor one family. My grandfather is no more.
The 3 sons decided to divide the property among themselves, so with everyones agreement one of the son took half land and built a house. The youngest one (who stayed on top floor) as well took the remaining half of the land and built a house.
So the oldest one by default got the old house. All the paperwork and registry is properly done for everyone.
There is one concern, when my grandfather was alive, around 25years back my youngest aunt had a fight with everyone and left the home. After coming back, they started building the top floor. Once the construction was completed my grandfather paid all the amount to his youngest son, but there is no handy proof as it was all in cash.
Now after all the division, everyone moved into their new houses, but the youngest one's family did not vacate the top floor and it has been locked for more than 2 years.
The oldest one, my father, who got the old house is stuck in this situation, that he is unable to get his brother vacate the house and causing mental agony. My father offered them the amount they want still they are not saying anything and causing a lot of trouble.
What is the best way out of this situation keeping everyone's dignity at the same time.