next/previous posts across subcategories

Hi guys,

I’m working on a journal kind of WordPress installation. My goal is to have the following category setup:
– edition 1 (no posts here)
– subcategory 1 (some posts)
– subcategory 2 (some posts)
– subcategory 3 (some posts)
– edition 2 (no posts here)
– subcategory 4 (some posts)
– subcategory 5 (some posts)
– subcategory 6 (some posts)
– subcategory 7 (some posts)

Now I’d like to have previous/next post links on the single_post Template. But they should go through their own subcategory and on the last post show a link to the first post of the next subcategory. Once they are at the last subcategory they should show no more link. (Ideally there would be a link to the category archive of episode 1 in the first post of subcategory 1 and last post of subcategory 3.
E.g. all posts in subcategories of edition 1 should be circled.

Hopefully you understan what I wrote 😉 It should simply work like a magazine in the end with each episode being one issue.

Unfortunately I can’t get it to work… Do you have any idea. Help is very much appretiated.

Regards Sascha