One forum backend for multiple site
 

Is it possible to run one forum and have multiple sites use only certain forums while sharing others. For example

Site A will see local forums related to that area and a forum with national topics. Site B will see local forums related to that area (not that same as site A) and site B will see the same forums with national topics. They share the same user base and some of the same forums, but each site also has it's on forums/categories. Do I make any sense?

If you are hiding content based on domain, you will require multiple vBulletin licenses.