I am currently working with WordPress Multisite (MU), BuddyPress, and Commons in a Box (CBOX) to create a website around a central user base which allows users to form groups and create "group blogs" associated with their groups. I posted further details about this exact situation on this question here.
However, I would like to a more general question about the nature of WordPress Multisite installations, beyond the initial site or network home.
My question is whether or not the default subdirectory url structure/folder can be changed at all.
For instance, Multisite's current default setup is site.com/blog/sub-site/. I am curious to know if that can be changed to say site.com/blog/enter_something_here/sub-site/. Furthermore, can this structure be changed to something that is not hard-coded in such as site.com/blog/current_user_name/sub-site/?
I am not looking for domain mapping and I have already seen the plugin which removes the "/blog/" from the Multisite slug.
I think what I want to know is how Multisite accesses or directs to subdirectory installations.
For instance, I changed the url structure passed to the creation of a new blog such that afterwards, using PHPMyAdmin, I could check that the blog registered the altered permalink structure as its url in the Multisite database. Similarly, the same url was in the link on the main site page however when I clicked on it, or tried to go to its wp-admin, I got a 404 error.
Is the url structure for subdirectory sites something that can be changed? (Even if that means editing core WordPress files?)