Father property distribution

My Grandfather has 2 son and 4 daughter. grandfather expire in 2005. he didn't make will for the property. we leave on flat which is named my grandfather and uncle name. In Agreement my grandfather name is firt and second name is my uncle .but property is brought by my father,grandfather and uncle jointly in 1989. 70 % payment done by my father. 20 %payment from my grandfather and 10 % from my uncle. after death my grandfather my uncle make notary and take release deed and give society.and make flat own name but problem is that now my uncle live in my father flat and we live on my uncle flat name ..but now all sister ask for her rights on father property.my grandfather written in his dairy the all property buy with amount who(myfather,grandfather& uncle) invested how much amount during buy property. we ask for father investment. but they all say 50 % is uncle right and other 50 % done 6 part. so it is injustices to my father.my grandfather never file income tax...my father had all income tax return...but for this property buy he make payment from selling of other property in 1978(which is name of my father) and buy shop in my grandfather name and sell those shop and its invest money in this property(at where we live).My Father done one mistake he took this property in Name of my grandfather & my uncle.so now how we get justices for this.