Using Mystic as a Hub

I recently switched over to using Mystic as my hub.  When someone joins the 
network, I 
want to find an easy way to ensure that all of the conference areas go to all 
of the 
downlinks.

If I go to the Message Base Editor and select by Network, then Global, is there 
some way 
to mark the field 'Export Add' to add all of the downlinks at the same time?

I tried hitting the TAB key to mark them, but hitting the Enter key afterwards 
just 
unchecks them without adding them to the list.

It's a chore to have to go to each conference area and add them one by one.

Mike Dippel