How to create "STAR Protected" area using OG+"OG-mandatory-group"?

1. Install module "OG-mandatory-group"
2. Create a new organic group e.g. "STAR Protected"
   •  disable it from registration form
   • set as "closed" - subscriptions are fully administered by an administrator. - then user cannot unsubscribe from this group
3. Go to drupal.star.bnl.gov/STAR/admin/og/og_mandatory_group and set up "STAR Protected" to be a mandatory group.
   [I checked that new user is automatically subscribed to this group.]

   So far everything is working as expected and I found no problems. There is just one more issue to solve .

4.  How to subscribe all existing users to "STAR Protected" group?
   I don't know if it's can be easily done in Drupal and the only solution I have in mind is to create a list of all users directly from drupal DB and then go to  "Add subscribers"  and paste this list.

Any questions?