Best way to add subscribers to main site

A while back I setup a dashboard blog for users to be added to with Buddypress.

Now setting up my membership site with the membership plugin, I see that out of my sites 2500+ members, there are only 372 added as subscribers on the main site, which means their is only 372 that I can add to a membership level.

What is the best way to get all my members set to subscribers on my main site?

I can delete the dashboard blog for starter (about 80 users there now), but then still missing the others?

Also if i delete the dashboard blog, where do the users of that blog go?

Wordpress MU use to give the option to move them to a certain blog, but I see that wp 3.0 doesnt do that.

Any ideas here?

Thanks,

George