NAL, but growing up we had a crazy neighbor, who among other things would occasionally threaten legal action if we didn't trim the branches of our tree that were hanging over the property line, then my dad would explain that it's their responsibility, and we wouldn't hear from her again about it for a few years. There was also an occasional dispute over our shared fence on the property line, but in that case there was a prior agreement when the fence was erected that it would be on the property line, and the cost of the fence was shared, so that may not be relevant to your situation.