If you try the group hierarchy mod perhaps so.. but each forum would belong to the subgroup. So that might not help you.
There’s also this plugin for stand alone forums: http://buddydev.com/plugins/global-forums/
I know it’s not the answer you might have wanted but it’s something to work with. The way BuddyPress is designed the forum is the official discussion board for a specific group. I visualize them as interest groups so having more than one forum per group breaks their identity IMHO.
The way the main forums works, its like a post-scanner for all group forums so you would end up with something more confusing to the end user who’s seeing:
TOPIC | POSTER | GROUP
There is no section that prints the forum itself just the group. However you could try instead just using different groups so its like:
TOPIC | POSTER | Group-a
TOPIC | POSTER | Group-b
TOPIC | POSTER | Group-c
I recommend the Group Hierarchy mod then the parent group owner can still more or less control everything.