Do you have knowledge that a crime has been committed?
Your sister is living life as she sees fit to do. It's not a crime to be unemployed or an addict.
I can certainly appreciate your concern for the welfare of these kids. CPS is overloaded and underfunded with first hand reports of neglect and abuse. Your report seems to be based on second hand information and does not make clear these children are neglected or abused.
Is there some reason why those with first hand information have not called CPS assuming they have wittnessed abuse/neglect?