duplicate is easy. Setup like follows:

Category, in it a forum (a). Then create a sub forum (b) with parrent of (a). Next you create a forum (c) with parrent of (b) and limited access to Admins, Mods or any special group. A user should not able to enter and see postings in forum (c).

This look this:

[Linked Image from home.snafu.de]

In this example 77, 83 and 86 are my restricted boards and postings in theses boards show as postlist topic on 74.

The forum (a) don't contain any post. There are only sub boards in it. In the post of this level you see sub forum (b) and the last posting entry of the forum (b) contains topics from forum (c) even the user have no access to forum (c). So he can see whats going on behind his back.

Made this now clear? I can also grant access to my board to show you the problem. Let me now if you need more information.

my board: http://www.dragonclan-forum.de
my hobby: http://www.biker-reise.de
Ich kann bei Fragen zu UBBthreads in Deutsch weiterhelfen oder es zumindest versuchen