Division of property when there is no will

Hi My father and mother both expired without writing any will.. 80%of properties in my fathers name and 20%on my mothers name.. we family of 3 members 1st one is my elder brother(married) 2nd is myself (married) and 3rd my younger sister(minor-15yrs) my father passed away 2 yrs back without any will.. so now my brother is getting all the rents from 5 house and 1 shop.. and he made a lease with two flats without my consent.. at that time of my fathers death my brother promised me he will give few shares to me after 1 year.. but until now he hasn't given any.. when i ask for my share he says, there is a minor girl (ie;my younger sis) and till she is major we can not divide the properties.. and he takes all the rents and lease money too.. And my younger sister wants to live with me as my brothers wife treating her very bad.. kindly help me in this regard, is there a chance to share the rents and property? and how to get guardianship of my sis? my friends says i have to file a complaint with police in local station? is it so? Regards mridula