This answer applies to the Junior Program. A player must have played in TWO regular season Carolina Region events in order to be eligible to participate in a Regional Championship Event (which includes the East/West Championships and the Regional Championships). All participants in a Regional Championship Event must be full members of the Carolina Region (so a one-event member that played twice during the regular season would have to upgrade to a full membership in order to participate).
This answer applies to the Adult Program. A player must have played in ONE regular season Carolina Region tournament in order to be eligible to participate in the Regional Championships. All participants in Regionals must be FULL (Regular or Collegiate) members of the Carolina Region (so a one-event member that played during the regular season would have to UPGRADE to a full membership in order to participate).