Division of House and Shop along with business ( Leased shop & Partnership business running in it)

Hi, we are three sisters out of which two of us ( living in two different states of india) are going through property dispute with My Chacha's family and my youngest sisters in laws ( living next to our parental home) who have colluded. below is my question Q1.My mother and my aunt own two adjoining but separate lease deed plot (In Bihar) on which in 1992 my father and his brother built a common house. My mother is dead( in 2020)and my uncle and my youngest sister's in laws colluded to get an agreement signed (not registered as far we know but its copy was hidden by my youngest sister) from us since we lived far that we are swapping plot and now they are living in the side of house land owners are we three sister and wall was stretched and their land parcel piece of house is locked and keys are with my sister who is not allowing us ownership . how to take our 2/3rd division of this property since youngest sister is also with them? 2) My Father and my uncle ran a business (Partnership) in a leased shop in prime complex (Bihar) in name of my father and after death of my father my Uncle without our consent got the records updated as Joint owners in PMC and partnership was changed removing my father and adding his son( Allegedly as we dont have access to documents). How to claim our 2/3rd share since we two sisters are willing but third sister has colluded with them?