You have alot more pateince & tolerance.......I would not go out of my way to change anything I do for my 2 Dogs. Your Dogs need to walk for soooo many reasons not just the obvious for exercise but that is part of how we bond with them or interact. You have to stand your ground and defend you and yours, your "Territory"! I would have called "Animal Control" the first time, I do not take any chances with mine. As far as your actual walk or any where in Public on a Leash, my 2 are very Friendly and fearless they will approach any and all other Dogs if I let them? Since mine are well "Socialized" with both Humans & all other Animals. But if I feel uneasy, I always listen to my "Instincts/Gut feelings", I would rather be Safe than Sorry. I know to other people whom do not have Yorkies, I seem very over protective especially b/c I know my Dogs, and what they will tolerate from others. Never take it into your own hands, let the Authorities deal with this Owner and his irresponsibility issues. They are not going to put the Dog to sleep for jumping your fence and marking your yard, but who knows how many other times he has done this while you were not Home? And how many other neighbors back yard he does this to? You are probably not the only one, I doubt if he singles out only your back Yard only? Besides who knows what else he does? By you NOT Reporting it you are just making the Problem worse, I'm not Lecturing you, many YT. Members are very Sensitive and I try not to judge or offend anyone with my comments. (Sorry I had to put my personal disclaimer in there some where?)
Can you tell I'm the "Alpha" pack Leader? Good Luck! Aloha*