Nothing changes. When zone boundaries intersect, each zone stays fully independent for monitoring, notifications, and messages.
That is deliberate. Each asset can have its own team, its own contact list, and its own emergency response plan. If a fire touches two intersecting zones, the system sends two alerts, one per asset, even when both zones use the same contact list. The same person gets two messages and knows exactly which assets are threatened.
So draw each zone to fit its asset per your ERP. Overlap costs nothing and merges nothing.