I already gave one example of a way to enforce it in my original post: require any resale to be mediated by Ford/dealerships. That is exactly one pivot table ha

I already gave one example of a way to enforce it in my original post: require any resale to be mediated by Ford/dealerships. That is exactly one pivot table harder to enforce than the no resale provision itself, right? You could do a bunch of other stuff, too. E.g., require Ford to be notified of all sales. Again, this involves the impossible difficulty of one extra pivot table.