P.K.
My husband's cousins have caused a similar problem in their family. The kids get into physical fights with everyone. They steal, lie, and tear up anything. their tantrums stop whatever is going on. You can't take them out because of it and most of the the family won't allow the kids at their houses even for Thanksgiving. The parents have drug problems so the boys have basically been neglected. My husband's aunt (the dad's mom) told the parents that she'd take the kids for a month and sent her son and DIL to try to work out their issues. They paid for an extended stay hotel for them because they all live in one house like yours do. It's made a big difference because their grandma is in charge instead of all three adults trying to parent against one another. I'd suggest your family give the idea of giving your sister some time without the responsibility of her kids. As long as she can use the kids as a way to not deal with the past she will. Therapists are really great but there are a LOT of support groups out there for widows and for children who've lost a parent. Convince your sister to go to one meeting and if she hates it she doesn't have to go back. I think she'll see that other people have been devastated by a loss of a loved one but have been able to manage their lives thru their grief. If your parents (or you) want to help then they need to step up and say 'my house my rules' and take your sister out of the disciplinarian role. It will be a relief for everyone. If it's possible to get your sister out of your parents house do it. Leave the kids with your parents and have your sister stay in your home for a short time. She sounds like she hasn't moved on past the first day she moved to your parents house. Losing a husband must be an incredible thing to have to deal with but would their father want the life they have now? ask her