BuddyPress and WPMU Memberships Paying Members Exist as 2 Membership Levels

Hello - on the website http://www.suspicious0bservers.org we use WPMU Memberships and BuddyPress to have a single, paying members-only forum. Many people are complaining that while they can join the group - whenever they go to the Group to post a comment or whatever they get blocked by something saying it is for paying members only.

I actually discovered (and fixed manually for a single user) the issue by realizing he was a member of two access levels simoltaneously - by deleting his subscription to the Free membership and leaving only the Paying one - he said it worked fine.

My question then is two fold - do I need to add the subscription plan "Free" into the box labeled "Starting Point" on the Memberships Subscriptions Plan screen so that going in the future new members do not exist as Free and Paying members simoltaneously?

Secondly, is there a better way than to just to go manually person to person and edit each user's membership information to remove the Free access level/subscription plan and leave only the paying level/subscription? There are several thousand and I don't even think it would be feasible to do that manually!

Thanks so much for your response,