co brand white label

Hey, I have a very simple minimalist site : [login to view URL] What I'd like to be able to do is to co-brand the site. For example, if St. Generic Church partners with my site, then I can create for them [login to view URL] and they can create a link to this url on their own website. When anyone enters via that url then I want the following to happen: - a different header is used (or different header elements - mainly a different header .gif and an additional link back to their own site) - the url continue to show [login to view URL] which will also require that - all the links (including the menus) have the subdomain added Other than that, I want the experience to be exactly the same as if they had entered via thetrinitymission.org. Additionally, - I only want to post once - I don't mind if it takes several hours to set up each new client - new clients do not need admin access - i'm less concerned with SEO (repeat content) than with getting the idea to work - I already know how to set up the subdomain stuff, it's the WP swap out stuff I'm needing help with I've called several wordpress designers I found on the internet and the responses I've received are either "it can't be done" (really??) or you have to use multisite (which I'm almost certain this is not what multisite is for). Is this something you'd be willing to do or to charge me to guide me through the steps. Thanks for your time. -michael