That is what I want. We are creating a website for a youth soccer club. Each team in the club can then manage their own mini site with team news, calendar, photo galleries, etc. However, the overall theme needs to be related to the club. Obviously we don't want team managers from one team editing content for another team. Trying to explain to team managers how to make sure they post content into a specific category or add a page as a child to another page is quite difficult (although you would assume it's quite easy). These are really novice web users and the separate admin ensures that things are a bit easier for them to understand.
Anyway, I did figure this out. It took a lot of searching to finally find the answer:
<?php switch_to_blog(1); ?>
<?php restore_current_blog(); ?>
This did the trick in the header.