Multiple subscribers to the same event

I'm trying to make a system for handling user settings(bunch of controls). The same settings will be implemented two times for two different environments and will control the same logic and contain the same properties. When user change value of some control in the first settings, some changes are made in the program logic and additionaly a control that handles the same property from second settings should be updated. Simple diagram:

So it looks like there are two subscribers(Settings A & B) and three listeners(Settings A & B, Event Handler) for single event .

What would be the best way to implement this?