Recite complete Surah Fatihah 41 times between the fardh and sunnah of Fajr salah with durood 11-11 times before and after and blow it on water and give it to your sister to drink, as well as give this water to those who have knee pain. If someday due to any excuse you do not get time between the fardh and sunnah of fajr salah then just do it after finishing Fajr salah. And if you could not do it any day, ask anyone else from amongst your family to do it. And after each salah and before going to bed ask your sister to recite surah Quraish 3 times with durood 3-3 times before and after, and blow it on hands and pass her hands over her body. And she should sleep on neat and clean bed according to sunnah.
Allah (Subhana Wa Ta’ala) knows Best
Darul Uloom Deoband