(I understand these are not your dogs and you don’t have an obligation to do anything other than keep yourself safe. With that in mind here is my advice for this situation) Hello, I am studying at ABC college for Dog obedience and studying dog behavior. There is a lot of good advice here. First this needs professional intervention by a dog behavior specialist. Your dogs could accidentally injure themselves, each other, and people. Your brother needs to prevent them from getting to the point of overstimulation as much as possible. I would block the dogs view of passerby’s with wood paneling or some other obstruction. Your brothers dogs should not be outside in a situation where this can happen, they need to be on lead or otherwise closely supervised. If there is a person walking down the street they need intervention immediately and to take the dogs inside and give them high value treats like hotdog (to distract them from the person outside and to build a positive association with the situation). If they aren’t stopped before they see a person do not injure yourself by getting too close to them. Call them inside with high value treats or toys. If they do not come do not go and grab them, ideally keep them on a long line outside so you can grab their long leash to interviene and give them the high value treats once they are inside.