From the book of rules:
14.7.6 Subject to this clause 14.7, the following changes are permitted to a Classic Flight Reward flight before departure of that flight, provided the booking contains one or more Flight Segments that are not within Australia, and the Flight Segment(s) being changed do not include a partner airline that requires a ticket to be reissued for the change. Any such change will incur a Change Fee (see the Fee Schedule) per passenger:
(a) change to flight number; and
(b) change to date of travel.
The complete rule book can be found here: Frequent Flyer Terms and Conditions | Qantas
