I participated in a similar type of cache, but it only involved two cachers and three locations... two for one cacher and one for the other. And they both get to log the cache and then log the sister cache! Check out:
With a Little Help from a Friend - in California GC17TXP http://tinyurl.com/5qzaab And it's sister cache... With a Little Help from a Friend - in Virginia GC17TXE http://tinyurl.com/5q89am