Thanks for your questions and for the details you provided regarding your application. I was able to match the plugins you mentioned to these free versions:
Formidable Forms – Form Builder for WordPress
By Strategy11
bbPress By The bbPress Community
Are those right? Are you using free or premium versions? Are you using any add-ons for media support? I hope you understand that I cannot afford to purchase premium plugins and themes simply to provide support for my own free plugin.
You wrote “user upload of images via Formidable Forms and via bbPress discussion groups.” I assume this means that your users are uploading items from the WordPress “front end”, not the admin area; is that right? I also assume the users have a WordPress user account and are logged in when they do their uploads; is that right?
As you probably know, MLA provides taxonomy support for Media Library items and includes two taxonomies (Att. Categories and Att. Tags) for your convenience. Any other custom taxonomy can also be supported. MLA can extract term values from IPTC/EXIF metadata, but this probably is not useful for your application.
The most likely solution for your application is a small custom plugin that takes advantage of the hooks provided by WordPress, MLA and the other plugins to determine what group(s) a user is in and use the results to assign taxonomy terms (or custom field values) to items as they are uploaded. I have done similar examples for BuddyPress in the past. You can look at the “Alexa Paige Plugin for BuddyPress & rtMedia” and the “MLA BuddyPress & rtMedia Example” plugins to get a sense of that work. Go to the Settings/Media Library Assistant Documentation tab and click on the “Example Plugins” link. Then type “buddypress” in the search box and click “Search Plugins”. Use the “View” rollover action to see the usage information and code.
I will be out of town and away from my development system until December 11 but I can give you more specific help after my return home. If the above suggestions are of interest, any additional details you can provide would be very useful. Thanks for your interest in MLA.