RosieRad:
It might be fun to do a co-authorship challenge sometime. It could lead to the development of some interesting new alliances.
It's perhaps not a smart move for a Challenge. I know of some people who've had bad experiences co-authoring. Their co-author didn't deliver on time, went off at a tangent & deviated from the plan, turned out to be terrible at punctuating dialogue etc and expected the other person to sort it ... etc, etc. Plus, many writers actively want to do their own thing. I co-authored an ebook with DJ Black - The Lord and the Librarian, and that worked out pretty well and was fun to do, but even so, I much prefer writing solo. But there's nothing to stop you from co-writing a story for loading on the library, if you can find someone with similar interests and writing ability.