Should be easy enough to sort out by reference to the deeds..... the land'll be registered now anyway if they're reasonably recent purchasers so anyone can examine the land records. If they own it, they own it. If they don't, they don't. It'll all be in the paperwork.
Be a bit shortsighted, though, for someone who's just moved in (if that's the case) to overturn accepted local practice. Negotiation would seem to be the way to go.
An Englishman.
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