Severe Domestic violence since 12 years

What are brother, fathers rights under Domestic violence if sister denied in fears. My sister are troubling since 12 years from her husband, mother in law, all members. It's literally physically harassing, kicking in front of me,insulted us many times, she never call to us, she has physically under nourished, weakened when consult doctors eeg reports severe even she looks like old woman under 30. Her family members have doing superstition practices voraciously..... Not only with my sister they harassed her sister in law (devar's wife) also. She also harassed by her husband, mother in law and all. She had taken poison once. Not contact her father's last 3 years. Both of she is leave home once but it failed. Our mistakes is we have lots of patience... But nowadays problem is both of she is undercontroll to their families when we meet her she both not agree to convey them although she's (both)suffering ....they controlled by her with superstitions whether we don't believe that...she deni