And, there is nothing at all stopping you from having the <master> of a <slave> in turn be the <slave> of another <master>, and propogate <property>'ies all the way up the chain. In fact, the intermediate master(s) can even conditionally modify what properties they pass up depending ones they receive, providing for defaults if the original <slave> doesn't pass anything up.
It's a very handy facility. As are <include>'s. 😊