Regarding distribution of parental assets. How to proceed?

Sir, My youngest brother and his wife are occupying the whole portion of residence which pertains to my father and to be distributed between us two as other two brothers had taken their share and he had extracted more than Rs. 1.5 lac from s.b account of my father my blackmailing him and now my brothers wife is blackmailing us that either give me all residential land or i shall commit suicide blaming your father and ur brothers .And you all be behind the bars. Kindly suggest what action should we take to protect us