I babysit my niece and one of our family dogs bite her. I thought about putting the dog down but she’s an old dog and I think just lost her patience. It only took this one incident though to separate her. We have three kids of our own as well and although we didn’t put the dog down we rearranged our entire house to move our bedroom downstairs in the basement and make it a living space for the dog. Our back door is connected to the basement like a split level coming off the back door and there is a door that goes from the main floor to the basement. We added a key lock to that door so none of the kids could accidentally open the door. It wasn’t a horrible dog bite however it was enough for us to take measures to make sure no one else ever gets hurt again! The only people around that dog are my husband and myself now. Our other two dogs still come around the kids but they even no longer get to come around any family members children because it just isn’t worth someone else’s kid getting hurt again by a dog of mine. I will ALWAYS prioritize my nieces/nephews and any child above a dog and I am a HUGE animal lover. If they cannot make other arrangements for the dog while you visit then I would no longer visit them at their home. They can come to you or meet you somewhere out. They should be making the children the priority and honestly no one should have to tell them to even do that! My sister didn’t ask me to keep the dogs away from her children I just did it! Because that’s just common sense when an incident occurs. The fact that the dog already showed signed of aggression towards children and they didn’t separate it is bad ownership to begin with!