From the FEATS rules:
It shall be written by a member of the participating group.
Its original production shall have had its first public performance within the previous two years or at the current FEATS; and it shall have the same director, set and interpretation that it had when first performed in public, although individual cast members can have changed since that first performance.
A longer discussion on the notion of original script is published here, with the approval of the FEATS steering committee.