How can I mediate between Mediators? or is it wrong design at first place? [closed]

Above pic is current situation of my classes.

I think, in near future, more mediators will be made.

My question is, (1) just one mediator should hold and communicate every other colleagues? If not, how can I communicate among mediators?

The answer of mine is that when a function called, check the function name and if it doesn't exist, call super mediator and repeat it in depth. .. and I think its quite ugly.