The humane society follows the animal protections act, which primarily looks at 4 things before seizing animals. I'm paraphrasing here but you'll get the gist of it:
1) Access to food and water
2) Access to adequate shelter
3) Access to vet care
I'm sure there's more to it than that but that's my low level understanding of it and it doesn't sound like it applies here. Since you've tried talking to him, the only other idea I have is maybe you could clicker train them?
It's a positive reinforcement technique where once they perform the task you want, you push a button on a clicker device and then give them a treat. It's not gonna be a quick fix but it would work over time. Karen Pryor is a well regarded dog trainer,none of that Cesar Milan crap. Maybe this is something you and ypur neighbor could work on together.
https://www.clickertraining.com/node/3968