Here are some resources for you and your family - hope this helps:
If you need legal advice on how to help your sister - here are two resources - call them and ask for advice given the situation (I’m assuming you’re in the USA - if not, let me know):
Treatment Advocacy Center
http://www.treatmentadvocacycenter.org/index.php
200 North Glebe Road, Suite 801
Arlington, Virginia 22203
Phone: (703)294-6001
NAMI (Call your local / regional / state office)
https://www.nami.org/
First Aid for Psychosis:
http://www.schizophrenia.com/sznews/archives/005561.html
and
and be sure to watch these videos (really, for the entire family at your house) from Dr. Xavier Amador:
and
and get this book: