Harrasment to my mom and dad by older brother and his wife.

Dear Sir/ Mam my father is retired from last 10 years from government job. my father has two house.1 house on my father name and second house on my mother name. but my mom and dad don't want to give property to my older brother and his wife as well as my younger brother wife. my older brother is my father’s first wife son. after death of my father’s first wife my father legally married with my mom and then after my father and mother got two sons me and my Younger Brother. My older brother and his wife regularly came at my home and harassed my mom and dad for property. Me and my wife take responsibility of my mom and dad from last 10years. so please guide us. how they save their property as well as take relief from their regular harassments.my father is senior citizen.