I am in the process of redesigning a site in Wordpress for a client. The client owns two domains - same but two extensions (.co.uk and .org.uk). The hosting package is on the .co.uk extension but they have decided they want the .org.uk to be the main address with .co.uk forwarding it. In Wordpress I am able to specify a site address that is different but this causes the site to show in a frameset. This is not ideal as the page address doesn't show in the bar at the top.

Is there a way to address this that's not going to muck up the database and existing content?

Thanks for your help.