[oXygen-user] XML Schema & XInclude ?

I have an xml schema I've created. I'd like to have several XML documents that are combined into a larger one (I do this with DocBook & chapters). But I can't figure out how to do this with XMLSchema. Basically what I have is one xml document per environment (it's for configuration information). I'd like to have a parent document that has elements from the schema that are generic to the overall base, then includes the several smaller environment xml documents. Any ideas? Thanks!