Adultery committed by my father and future will

I am Meghna Nair, 23 born in Mumbai but raised in Bahrain and currently I am residing in Mumbai and working as a credit rating analyst. My father has established his business at Bahrain and I had stayed there for 17 years with my family (mother and brother) My brother was diagnosed with borderline mental retardation when he was in his 8th grade and has completed his SSC but is currently unemployed. My mother is a housewife and never worked after marriage. When I was 5 years old my father left us for another woman who was working in his company as a secretary at Bahrain. He has two daughters with her and my parents eventually separated but never got a divorce. Since then he has been helping us financial by providing us with a certain sum of money every month. After I completed my 12th grade My father asked me, my mom and my brother to shift to Mumbai, where my mom has a house in her name. Reluctant to shift yet left with no other option I moved to Mumbai with my family and continued my graduation and post graduation degree here. Now my father is approaching his 60s and what worries me are the following: Future will - In whose name shall he transfer the business and the property and how can I ensure that me am my family (brother and mom) get most of it or the entire property as we are the legal heirs. We have always been kept a level lower than the standard of living they have lived. (My dad owns a BMW and his mistress has a Lexus and various other properties in Bahrain and India. She is now a director of my father's company as well). Thus how can my dad be penalised for his discrimination in providing luxury and comfort. My father never cared for my brother and he could have given him a job in his company yet afraid of the shame to display to the public the fact that his son is NOT NORMAL he never did anything for him. And most importantly the pain caused to my mother and how can she get justice for her sufferings from the past 20 years.