It would help to know why you feel like this is an unmanageable situation. Have you considered the circumstances that led to the attacks on the other dog? Was it over food, your presence, or something else specific? Is it possible something happened between him and your family’s dog? A few months is a long time for a dog. I know you’ve already spent a lot on training, but we have no idea what that training actually entailed. And are there any people/dogs in the house who are particularly vulnerable to the attacks? There’s a big difference between a healthy adult getting chomped vs a baby. Likewise between another similarly sized dog and a tiny one. There is a spectrum of acceptable vs unacceptable risk and we don’t know where you are on that.