You've already got a bad neighbor problem, so it doesn't matter what you do from here. Call the authorities. If the dog comes onto your property, catch it and call the local animal shelter to come pick it up. Can't make them dislike you more than they already do, so it's time to stop worrying about them and do what's right.I supplied materials from my scrap lumber masterpiece coop so they could build one, finally when I offered to help ( I did 75% of the work) we got a coop put up. I did the basic walls and told them they needed to do te rest like a floor in the coop and roosts etc, that still isnt done but its up and the birds have been in it for 2 months so cant do anything there.I am stopping all comunication with these people, today I got word that I am no longer to throw food in to their birds, that they are perfectly capable of feeding their birds. I was accused of stealing from them and that I am not to come on their property.. So back to plan A call the authorities..
It sounds to me like you've done your absolute best to maintain peaceful relations with these folks. Time to give up that idea. And who knows? Sometimes nasty neighbors get what they deserve. My horrid neighbors that used to have loud parties at 3am on weeknights and shoot fireworks so they'd land on my barn roof and throw their scrap wood and trash into my pasture lost their house when the guy went to jail... couldn't have happened to nicer people, and karma can be a wicked mistress. Now we have a VERY sweet young couple living there.