Problems with a couple of neighbors, what should I do?

I would collect all the poop witha shovel and put it right in front of their door. Then put a note over it saying the next time your dogs poop in my yard Im calling the police. Get a video camera (or camera or webcam) and tape them running around loose for proof. As for the kids just talk to the parents about their kids leaving stuff out. WHere the hell do you live btw it sounds like a nightmare.