I signed up after myheritage took over verwandt.de , so I only have a myheritage account.
When trying to look at a family tree of a member where it says "Familienseite (verwandt)" in his profile, I'm being asked to login to the site - and my myheritage credentials don't work !
If you find a Family Site that has information that you are interested in, but is blocked to the public, you will need to contact the Webmaster of that site to request membership. You can do this by going to the bottom of the login page for the Family Site and select "Contact Webmaster" link. Fill out a nice message with the reason you would like to be a member and submit.