^Yeah that loving father, if he wants to really be a loving father, will step up and get the children out of that dangerous and volatile environment, he'll be the next person the Prosecution charges with felonies given that he knows what's happening and may or may not be trying to help his mate, but Love is blinding, so blinding that he's not able to see that there are children involved here and that in no way shape or form is he doing himself, his children, or his wife, ANY favors by not IMMEDIATELY getting those innocent children away from their mother, through whatever means necessary and
I mean that. No one likes to have to call Child Protective Services but if there's one situation where I never hesitate to make the phone call, it's this EXACT scenario, and I have no faith that the parents or guardians of the children are going to do what they should be doing. Consider coordinating some personal days off with the father and take the kids on a trip under responsible supervision of a sober adult, take a small vacation or road trip or something because if at all possible, and TRUST me on this, you do not want them to be around the mother when CPS, Social Services, and/or the police show up to investigate your sister's home and whether the environment is suitable for children.
I am also not pro-intervention or anything, but as I've said, this is a serious situation where you have the moral and ethical and LEGAL obligation to provide a child safe environment or immediately attempt to reach out to the correct authorities for help explaining the gravity of the situation to your sister, hopefully before anyone, be it the city or state etc decide to press charges or take punitive measures that will affect ALL of you and by doing so, you risk having the kids being taken away from their mother and be put into the system which will change their lives FOREVER.
Your sister has a choice to make. She made the choice to abuse methamphetamine. She made the choice to have children, and try to raise them at home with the father figure, but as you know, this clearly isn't a have your cake and eat it too situation. When you have kids, the choice is simple. You choose rehabilitation/addiction therapy and get to keep your family provided you maintain sobriety and a child safe environment, OR you choose crystal methamphetamine. It is THAT simple. There are children involved, local, state, and federal laws ALL are EXTREMELY straightforward about child endangerment, contributing to the delinquency of minors, child abuse, neglect, etc.
It's meth or the kids.