conditional combination of common lisp pages in webactions

Ok, here's what I've got:

  header1.clp  header2.clp

        content.clp

  footer1.clp  footer2.clp


...and I'd like to combine them in various ways, such as:

    header1.clp + content.clp + footer2.clp

You get the picture.   However, I don't want to embed that logic in
content.clp as it boils down to business-logic which I want centralized.

How would you suggest I go about this?  I was planning on putting my
conditional logic in action function, but can't seem to quite get it to
work as it appears that parsing plus the application of CLP variables
are seperate steps.  I think that leveraging the compiled functions
would be a good idea but haven't gotten that far yet.  (It also looks
like I can't include a CLP variable inside of a CLP_include)

Any pointers?  Thanks,

- Heow