Will by mother

Respected Sir, My father bought a plot Land in the name of my mother and made a house for us in Tanakpur, Champawat, Uttarakhand state. Our land is not registered land it's class 4 land and it's an agreement on stamp paper. I have one younger brother and elder sister. My mother died on 05.04.2017 and before her death she made a will where she has given this land and house in name of my younger brother's wife. But the will is not registered in registrar office , only notary has been done. And one of witness is mother in law of my brother. Now they wants to take me out from home and wish to sell this property. Even our land is not registered . So please help me to know that Can I get half of the property (land and house), as my father is alive and wants to give me 50% of this property. How I can claim my part. As will is also not registered. And proper was purchased by my father in name of my mother. She was not working women, she was a housewife. I am still living in that house with possession of 2 rooms. Please help me and guide me. Thanks.