But you did two things. you searched on the Internet and called your vet. I don't see how you could bring the two remaining ones into your house with Lily and Luna; what if they have health issues? You couldn't risk making your cats sick. That might also create more conflict between you and the neighbors. Maybe the regional authority would take action, since the weather has been so cold. It sounds to me like the only other thing you can do is urge them to take their pets indoors.