Display all posts from subforums in parent forum

[AshAbed]

Lets say I have a forum named 'Forum 1' with the subforums 1,2,3,4,5.
I'd like to keep the subforums 1,2,3,4,5 all hidden forums and I'd like it for every thread created in them to show up on the parent forum. I don't mean a copy of the thread - a simple link to the subforum would even do, as long as all threads from all subforums are displayed on the parent forum.

Thanks for any help.