Regarding illegal occupancy of house

Hi , My query is regarding a family property division dispute , After my grandfather died in the property was to be divided among his 3 living sons and 2 living daughters , And it was divided among them after several measurements and discussion ( 2024 : still not documented, it's just your land there and my land is here on basis ) . The 1st son works in The Armed Forces , The 2nd son has fish business , 3rd Son is jobless The dispute is between the 1st son and 3rd son , After the division of property there was a need to build a new house so the 1st son built a house for his old mother with his own money on 3rd son plot ( as it was empty) because on 1st son plot there was the old house in which the 2nd son was still living with his family separately. After the 1st son built the new house with his own money it was logically decided that the plot which was earlier given to 3rd son will belong to 1st son now as he has built the new house with his own money and 3rd son got to a new plot where he will build his home in future. Their mother died in 2013 after that the 3rd son started to live in the new house which the 1st son built , as he had nowhere to go and the house will remain empty as the 1st son works in the Armed Forces In 2015 the 2nd son built his own house on his own plot with his own money and the old house was finally dismantled In 2022 , the 1st son even built boundary walls along 4 sides where the new house was built back then Now in 2024 , when the 1st son asked 3rd son to leave his house and build his own , the 3rd son is abusing and blackmailing the 1st son to give him money or else we won't leave the house and will occupy 2 rooms of it , and says he got the plot first when all the land was initially divided among the 3 sons As I mentioned the 1st son works in the Armed Forces and goes hometown with his family for a month or so in year , and is paying all the expenses like electricity bill of the new house which he built back then What can be done to legally remove the 3rd son from house , I have mentioned earlier that no legal ownership papers have been made as to which plot belongs to whom and who is the owner , its just mutual consensus between the brothers that this is your land as you have built house there and this is mine I have mine here It would be a great help , Thank you.