I would like to book a return sydney to singapore business/first class ticket. Given that tickets are not that easy to find for classic rewards, I would like to lock in the dates. However, I am not 100 per cent sure that I will be able to travel on those dates as there may be projects that may come up later. Has anyone tried changing the dates after booking a reward flight? Thanks 
Hi. Can you book an economy reward flight and change it to business if it comes available later…can that be done online?
Yes, this is absolutely possible and one of the best things about points redemptions - there flexibility of changing (if there are other award seats available).
The Qantas change fee is 3,500 points per person, and the cancellation fee 5,000 points. You’ll pay any difference (or be refunded) in taxes also.
Changes for some redemptions can be done online, others need to be done over the phone.