You have a few options. It depends on how you feel about shooting/killing the dog. For non-lethal means you can try HALT pepper spray, paintball gun or shotgun loaded with rock salt (or beanbag gun, etc.) There is also the SSS method where you shoot the dog and don't tell anyone you did it. (Shoot, shovel, shutup)
We had a similar (but not family) problem here. The neighbor would promise to keep his dogs contained, but that only lasted a few day. We figured it would take a car accident or shooting for the neighbor to care about keeping his other dogs penned up. One day we saw a notice posted by our mailboxes. It said that someone murdered his dog with ANTIFREEZE! If your family is truly crazy about their dog, they must keep it contained for it's own sake. Surely you are not the only neighbor being annoyed by this dog. I wouldn't begrudge anyone shooting a threatening dog, but death by anti-freeze inexcusably cruel. There are some real sickos out there.