sister share in property

Sir please advise what will b the legall share in my fathers property I have 1 younger sister and she is married and I have ELDER sister she deid last year please guide my father is going to marry again and we want the distribution of proprty before this marrige we are against this marrige and want to avoid it becase some people are missguiding him so please how we can file a pettion against this marrige and sale of property