Can voluntary changes be made to bookings after travel has commenced?
Yes, but its very restricted. Refer to the following extract from the book of rules (I think you’ll be most interested in the last part 14.7.6):
14.7.4 Subject to this clause 14.7, the following changes are permitted to a Classic Flight Reward after ticketing and prior to commencement of any travel and will incur a Change Fee (see the
Fee Schedule) per passenger:
(a) change to flight number;
(b) change to date of travel;
(c) change to class of travel;
(d) change to any Segment routing or airline;
(e) change to name (only for Flights with a Qantas (QF) flight number on the ticket that are operated by Qantas); and
(f) request to cancel ticket and re-credit Points. Please note that only Points that would not have expired will be re-credited.
14.7.5 Subject to this clause 14.7, the following changes are permitted to a Classic Flight Reward flight before departure of that flight, provided the entire booking contains only Flight Segments that are within Australia, and will incur a Change Fee (see the
Fee Schedule) per passenger:
(a) change to flight number;
(b) change to date of travel;
(c) change to class of travel; and
(d) change to a direct or indirect Segment routing without a Stopover (provided the origin and destination cities remain unchanged) or airline.
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.
For the rest of the rules, folllow this link:
Frequent Flyer Terms and Conditions | Qantas