Difference in Registered will and parti on deed

My mother (widow and senior citizen) got an apartment through registered WILL ( WILL made by my late grand father). The Will earmarked shares of 2 brothers of my father along with My mother's share (an apartment where is he currently living and also 50% share of one of the roof above top floor) and my younger brother who was beaquth one shop. My younger brother has been staying along with my mother in the same apartment since birth. A partition deed was executed and registered between my father's 2 brothers, my mother and my younger brother, based on the contents of the WILL ( 3 years after the WILL) and a site plan was also prepared which depicted the share of all the 4 ( 2 brothers of my father, my mother and my younger brother). This site plan is a colored one and has respective shares of property differentiated In separate colors. An error was made in the partition deed and the partition deed mentions in writing that the apartment along with the roof rights is jointly withheld by my mother and younger brother. This statement made in parti on deed is contrary to the WILL and also does not match with e colored site plan. As the colored site plan attached with partition deed shows only 1 shop. My younger brother filed a suit for his share in the apartment as well for roof right. Our case is in civil court and has been going on for last 1 year. Please advise what to do, so that my mother gets her complete ownership of the apartment and roof rights.