Joint roof cutting of 1st floor house

Hi sir, We have a stay in joint 1st floor house with my father and uncle but the partition is done and invivitulally legal partition paper have the both parties. Partition done only on paper but the house as joint property such like left hand stay uncle and right hand stay in my father. But on paper partition done equally of the my father want to do seperate by the partition wall and cutting the roof and it's practically feasible as per house condition. But uncle said that we can do the partion wall but not to cut the roof of house.uncle also treathing my father through lacal people and stoping the work, my father 60 year old person and put pressure on him that not to cut the roof. My father question is that I am working on my land area which are legally partitioned. Here I need advise , how to possible to cut the roof and make it 2 nos individual house? As a joint roof we are unable to construct the 2nd floor of house because my uncle not capibale to mainthis property and roof, so as joint roof, if my father construct 2nd floor, the 1st floor it's affecting due to non maintenance of uncle side, as per present roof condition not good as construct 22 year ago. Please advise me how to come out of this situation and cut the roof for seperate as phisically as well as on partitioned paper.