what it all comes down to is respecting other people and their property, and taking care of your kid.

you don't just waltz up to horses, especially strange ones, and expect them to be like the family pet. fences are to keep them in, but it's also to keep others out.
i would recommend, in this day and age of a litigious and careless society, that you double fence your horses and clearly mark the line with no trespassing signs.

or a moat...a moat with gators. i want one of those!