We recently got a new set of neighbours and they have two chocolate labs. The family seem overall pretty nice and they've come over to borrow some stuff a couple of times without much fuss.
A few weeks ago I started noticing piles of dog poop in the front yard. Not on the periphery but actually on the lawn and up around the side. The image below pretty much shows what our house is like compared to the neighbours, for context. I had a look at the security footage and sure enough it's the new neighbours, specifically their teen boy (looks to be around 16-17). He walks the two dogs off leash and we're the first yard they pass. He lets them wander up all the way into the yard since they both pee on the flower bed we have (pretty much the same location as those plants up against the wooden part). They wander pretty far up and around the side as well, which is where I have found the poop. I've also found poop on the lawn. It's probably happened close to 10 times now.
The boy just lets the dogs wander up the lawn and watches them, and when they come back he walks off. Makes no attempt to call them. He even lets them wander onto the porch where they will have a sniff and pee up against the front door/wall.
Would it be unreasonable to camp by the door and approach him next time? Or call his parents to complain? I don't want to muddy the relationship with his family but it's getting to be quite annoying. We don't have dogs so I don't have dog poo bags, I've been using generic plastic bags but am fast running out.