If:
(a) on AAT first review of a decision, the AAT sets the decision aside under subsection 43(1) of the AAT Act; and
(b) the Secretary or the AAT, as the case may be, is satisfied that an event that did not occur would have occurred if the decision had not been made;
the Secretary or the AAT may, if satisfied that it is reasonable to do so, treat the event as having occurred for the purposes of this Division.