First off, unless you have a specific reason to put the article-only text in child documents, I'd probably advocate including it in the original text file in branches (just to keep things together). If you have a particular reason to use child documents, then maybe put the child include statements in a branch (so you can turn them on and off easily).
I assume you only need to generate the outline thingy for the final presentation. Does the following produce what you want? 1. Once the presentation is done, save a copy of the LyX file with a new name (so as not to molest the original). 2. Change the document class from presentation (beamer) to article (beamer). 3. If necessary, delete the inclusion of the child documents from the copy (easily done if they're in a branch -- just turn the branch off). 4. Compile/print/distribute. This gets rid of the background stuff and cosmetic graphics. I'm not 100% sure it's what you're looking for, but it's easy enough to try. /Paul