Ok here's a better example of what I've been trying so clumsily to explain. I'm pretending that someone has volunteerd to be the editor of the Irish Bloggers node so I've broken that off into a separate OPML file. Then all I had to do was edit my original top-level OPML file to link to the bloggers files on-the-fly by inclusion (or transclusion).
So now, please view the HTML rendered top-level again through KBCafe and click through on the News & Media node. You'll see that the Bloggers sub-node is a blue underline and clicking on it brings up the full list of bloggers from TechCamp (plus a few more), with RSS subscribe buttons for convenience.
Looking at the file name below the KBCafe Surf form confirms that we are indeed now looking at the HTML rendering of another OPML file - IrishBloggers.opml. That's the power and beauty of OPML.