Two source documents with one stylesheet

I'm working on a project to produce an FO document. The FO document will have two fo:simple-page-master elements (one to produce portrait output and the other to produce landscape output) and will produce three fo:page-sequence elements. The input consists of two source documents.

What I hope to do is pass the URIs for these documents to the stylesheet as parameters and use them in two document() functions inside two variable declarations. Creating the variables works without a problem. 

What has got me stuck is how to use the elements in the documents defined by the variables. Specifically, I can't use a variable in the match attribute of a template and I can't think of a way to accomplish this task without that.

Do I have to first merge the two source documents, then process them with the stylesheet in a two-pass process, or is there a single-pass solution?

-- 
Charles Knell
cknell@xxxxxxxxxx - email