subsite categories on nav wide menu ?

Hi,

I am using multiple subsites, which are all linked to on my main site.
One of these sites, multimedia has categories and I wish to attach those categories to the menu bar under the multimedia section, so they show up on every site and page.

Is there a way to do this, the categories of the subsites don’t show up on the main site. if they could show up in the menu area of the main site that would help a great deal.