I'm using a plugin called Co-Author. This way you can add multiple authors to a page. I'm using this plugin to link users to their group-page (the author page is used as a profile-page).
But! this plugin only allows users with write capabilities to be used. Who can alter this plugin so you can also add subscribers?
I put the file here: http://www.sacredi.eu/co-authors.zip. I have a lead for the solution:
filename: co-authors.php between line 51 to 94.