Ayrabz, skydy had the right interpretation. I was just trying to present a no-emotion version of the situation, because the OP and followups, which yes I read, are full of statements about how others are in the wrong. No one’s doing anything wrong here. You keep horses on a small lot and are using it right up to the line–without any intention of being bad neighbors. Your new neighbors have the same RPA problem and they’re following all the rules (including getting a setback variance in accordance to all the rules) in order to get similar leniency that your grandfather enjoyed. Without any intention of being bad neighbors. They’re building their lot from scratch just like your grandfather did.
Zoning hasn’t failed you. Zoning’s kinda like the HR department of a company, that makes sure the rules are followed to make sure employees get equal treatment, and have a standardized process to consider exceptions. But ultimately they represent the town’s interests. And in general, towns want property tax revenue, so a completely unbuildable lot–when a reasonable variance is possible–is not in Zoning’s interests.
Sorry to have angered you further. Hope it all works out and that you end up with good, considerate neighbors.