well how it works is this.. .the source forum is where the ONE and ONLY thread resides... what the display does... it just grabs the threads from the source forum, and basically links it to your other forums...
you can see how it works at my forum:
www.l2blah.com - the announcements forum is my "source" forum, check out the other forums and you can see the global threads.
When users reply to the global thread, they are replying to ONE thread, that's actually located in the "source" forum; but the thread just gets displayed in all the other forums as well.
Things I will include in the next version:
1) Forum Exclusion
2) Display Properties
2a) more locations of where you can place the Global threads
2b) changing the text of "Global Threads: " to something else
2c) setting the sorting of global threads (right now I have them set to the time of creation instead of lastpost)