Brothers cheat sisters of their rights

We are a family of 3 brothers and 2 sisters. My father died without writing a will. After his death my mother did not want partition of a house built by my father out of his earnings till her life time as she was emotionally attached to the house. After some time my brothers prevailed to relinquish our shares in favour of mother so as to be able to manage the property. All brothers and sisters executed relinquishment deed in favour of mother. Soon thereafter brothers prevailed upon mother who was living with them and was dependent on them for her survival to write a will in their favour. She was taken to the office of the registrar and made to sign on dotted lines. She could not bear the pain of cheating daughters and confided the facts to her daughters. Brothers have since broken all relations with sisters. In the meanwhile mother has passed away. We two sisters feel cheated by brothers as we had relinquished shares on assurance of protection of our rights. Now what are options available to us.