One product, one outcome, whichever button they clicked

A payment tells us which product was bought, never which button or table column it was bought from. That means there can only be one answer to "what happens when somebody buys this". Until now the same product could carry a different answer per widget, and a purchase quietly applied all of them, so which newsletter setting you ended up with depended on the order they had been saved in. There is one rule per product now, and the database refuses anything else.