tell her that if she don't straighten up, you'll take all the kids and file for "child support" from her. why should you be taking care of the kids and she gets a free ride.
My daughter was living with her boyfriend and somehow after watching my grandaughter one weekend, it turned out into two full weeks and counting. She had been collecting child support from the father of her daughter.
I told her I was going to take grandaughter away from her through court, that she couldn't see her until she sobers up and that I would demand child support from her.
She came to pick up her daughter the next day.