Property partition-250 crores

Islamic Law My father had two wives one of whom passed away long back(my step mother) and one is still alive(my mother).The first wife had 5 children(3 sons and 2 daughters) and my mother has 8(3 sons and 5 daughters including me). My father too passed away in 1993 without making a will.Now my fathers property runs upto 70-80 acres(250 crores) around Bangalore out of which my father had registered 40 acres of land on all the sons during the time of emergency(1970's).Now my brothers do not want to give us any share.So we sisters have decided to take a legal course of action.Now I have a few queries. 1.Will the share be divided equally amongst the two wives of my father and then amongst their children( i.e us) or 70% to all sons and 30% to all daughters irrespective of stepson and steddaughter? (70-30 acc to shariah law) 2.One of my sisters does not want to be involved.So is it possible that 6 of us sisters can go ahead and file a case without her?Will it weaken the case?Will she get her share even then?If not what happens to her share? 3.Since my brothers have not earned those 35 acres themselves(no proof or source of income),will that 35 acre also be eligible for a legal case? 4.If proceeded in an upright manner,how long might this case go on for considering all the papers are legitimate and been in the family itself for 70 years. 5.What might be the loopholes in this situation? 6.How would the process for this kind of a case be?From start to end including payment and everything?