Setup for shared and exclusive forums

[islandcommuter]

So here's a mind-bender for a VB noob like me...

We are transitioning from custom forums to VB 3.7.1.

We have 10 web sites dedicated to different boat brands (in the auto world, this is the equivalent of having sites for Ford, Chevy, BMW, Toyota, etc.). These sites each have forums specifically for each brand.

In addition, we have a number of forums that are shared by _all_ sites. (see diagram -- may help, may not)

For reasons I won't go into here, we need one common table for users of all sites.

So, what might be the best way to set this up?

1. Have 11 installations and modify them to use a common set of tables. (expensive, high PIA factor, lord help us when it's time to upgrade)

2. Have 1 installation running under one domain and use permissions to hide/show some forums only to certain user groups. (seems perfect... BUT the site-specific forums would be invisible to guests... not a good way to sign up new users)

3. Add a field to v_forum named "site" with a value designating a specific site, or "all." Then, modify the appropriate searches to check the site field. (big initial mod cost, lord help us when it's time to upgrade)

Anything else that might accomplish this with less pain?

Thanks for your help -