I work in psych and while I have had patients with pseudo(fake) seizures, I have also seen ones with seizures from benzodiazepine (Valium, Xanax and Ativan are all benzo's) withdrawal. Your sister could be having either type of these. The best advice I can give you is that of tough love. It sounds like you're the caretaker in the family so this will be hard but you need to stop running to her side every time she has one of these episodes. Good luck.