My skitzophrenic sister?

My sister was wonderful before she was diagnosed with skitzophrenic disorder, the first time after the diagnosing that I actually noticed is when she kept calling me the name of her ex, I told my mom and my mom confronted her, she flipped, screaming about demons where coming, she took my moms purse and ran out of our apartment, when she returned $300 was missing in less than an hour of her disappearance. She refuses to take medication and her times "away" are getting even more long,and unbearable, do you guys have any suggestions for the situation? BTW she also has bipolar disorder and she hears voices...