((((artista)))))) I so feel for you and the children in this situation. Sounds like you are doing all you can to protect them. I can't imagine that they wouldn't keep your sister longer than 3 days in the psyc ward. She isn't only a threat to herself, but sounds like to others as well.
Addiction is cruel and heartless. I pray God will give you peace and wisdom through this storm and protect the children as well. Bless you for doing what you can. It is sometimes easier to talk to "strangers" for many reasons. There is much to be learned from these posts. I've been at this a long time, and I'm still learning. So hang around. No one here can "fix" it, but we do care and can be a support link for you.
God bless you. I care.