In a word yes, however be careful.\r\n\r\nmdiggity is correct in that once you book you get a reference number, and provided you have booked a premium economy fare you can then assign your QFF number and request the upgrade there. The fare type is what’s important, not where you buy it.\r\n\r\nHowever I would urge caution cause that sort of price difference is inherently suspicious. Qantas build into their fares a 10 - 15% margin for agents and OTA’s, and the reason why sometimes you find them cheaper through these avenues than Qantas is that the OTA business model is to discount the fares to net prices and make money off the ad revenue from their site. However $4000 worth of difference is enough to make me very very dubious - there is not that much margin in them, and no OTA is going to lose $800 per pax on a fare.\r\n\r\nI’m not saying there is something dodgy - it may well be fine - but tread carefully. A lot of OTA’s will sell you a premium mixed fare which can be hard to spot if you’re not careful (i.e. you might fly SYD - LAX in premium and connect onwards to NYC in economy, that’s why it’s cheaper). There are also certain sites out there which “sell” tickets, which are basically award seats they book using points and sell the tickets on to you. Because it’s a violation of QFF program terms and Qantas know people do it, they have been known to cancel the seats out from under you if they detect it, and in that case you are facing an uphill battle to get anything back.\r\n\r\nIf it’s one of the big guys like Expedia just check and make sure it’s not mixed, and check the aircraft types to be safe as Qantas only have premium on 747’s, A380’s and 787 dreamliners, then go for it and you’ll be sweet. If not, do your research on the company and pay with paypal if you can so you’re protected.