Can you help? Mash-up of RSS feeds...

We're gearing up to running a new round of 23 Things for Professional Development course, and I'm trying to streamline the sign-up process.

Sign-ups work as follows:

1. Person enters their details (blog title, blog URL, location, type of library work they do) into a Google form.
2. Someone from cpd23 team checks the details, and saves the blog as a link in Delicious.
• The Delicious bookmarks are useful for people looking for blogs to follow, and feeds from Delicious are used to maintain a list of all participants on the cpd23 blog, and a 'latest sign-ups' widget, too.
3. A task on ifttt.com takes new Delicious bookmarks and inputs them into a Google Reader folder.  (Reader will usually find an RSS feed direct from a blog homepage URL.
• A 'latest cpd23 posts'  can be created using Blogger's blog-list widget - pulling in feeds from the appropriate Reader folder.

This bit is all OK.  But last time round we also had an aggregated feed of all the posts from all the participants.  Now, as we had so many participants, the feed was *huge* and I'm not sure if anyone made practical use of it for very long, but it's the principal of the thing that I'm interested in. Last time, we achieved it by creating a Google 'bundle' of feeds, and then running that through a Yahoo pipe to make a single feed.  But keeping the bundle up-to-date was really fiddly (just because of the way Google organises things).

So, does anyone know of a way of automatically adding feeds from a specific folder to a bundle?  It's easy to do when you first set up a bundle, but if you add anything new to the folder afterwards (which we will be doing), then you have to add that manually to the bundle, too.

Or, does anyone know of a different, better, way to automate getting from a feed of new delicious bookmarks to an RSS feed of the posts of all the blogs thus bookmarked?