Changing the root domain in a network install

Hi, I set up a ProSites network with siteB.com as the original site, but actually it would be better to have siteA.com at the root. siteA.com is currently parked on siteB.com and wildcard subdomains are set up.

Is it possible to switch, or do I need to unpark siteA.com and start over? There are only a few sites set up so far and nothing that can’t be easily replicated.

Thanks for any pointers,

Neil