Often times, these things are dealt with without either party knowing what the true laws & land owner rights are, and this is not helped by the same often being very vague and subjective.

When entering into "negotiations" with her, you must know the legal backstop. Even if you play that part close to the vest, you still have to know what it is.

Some money spent now to know that is worth it.

Excerpt from Robert Crais' "The Monkey's Raincoat:"
"She took another microscopic bite of her sandwich, then pushed it away. Maybe she absorbed nutrients from her surroundings."