Part of this post is to vent and debrief, but also to gather ideas in how I should approach this situation.
We own a low set property. Our neighbours situated behind us have pretty free access to out property as there is no dividing fence. Their 3 kids (roughly 2, 4, 6 year olds?) are frequently entering our property without permission. We have to keep kindly asking them to leave on a regular basis. The eldest usually makes a few snide comments and leaves, but is soon back in our yard. No damage yet, but they play with our kids equipment and I often have power tools around the area that I sometimes forget to put away. One of the kids is ALWAYS stark naked so it's an unpleasant sight. We've spoken to the parents who seem OK and have apologised, but there is no visible change in these kids behaviours. They are still outside largely unsupervised.
The biggest concern is that while we were out, our other neighbour found the older kids running around on our roof and pulling on the antennae cords. When he asked if they're supposed to be up there the 6 year old apparently said "yes we are". Again no damage done, but I'm very concerned for the safety of these kids. I spoke to the father about the roof incident and he apologized, but then proceeded to talk about his long working hours and how his was had been sick which the kids "took advantage of". A week later, they were out in the back largely unsupervised again.
Now the obvious response is to build a fence. The neighbours promised this >6 months ago and offered to pay for it all, but nothing has been done. I've been telling him that we should pay for half. I've been trying to send him messages about this since, but have been getting very empty replies such as "Hello, thank you for the information" and nothing else. I'm thinking of trying to issue a 'notice to fence' and just get on with getting the fence built. Anything can be done about the trespassing in the meantime? Especially with the risk to their kids, the indecent exposure (naked kid).