Some may remember a few days ago I asked whether a flight amendment could be put on hold with USDM whilst you already had a booking. I rang up USDM and was told no.
The leg which I wanted was DXB -> LHR on QF1. What was interesting is this leg showed availability on the BA/AA tools, but not on the QFF tool. JAL tool kept coming up with an error message so I couldn't use that.
Given I already had a booking routed via AMS, I didn't want to pay 2 changes fees whilst I waited for my return leg to open up coming home from Vienna via Doha.
What I did to ensure that flight was still available was use my AA account to put the flight on hold online - which you can do for up to 5 days. Then the moment I rang USDM to make my changes, I simply logged on to AA site and cancelled the hold and the seats reappeared.
My fear was that the seats may not come back to award inventory once the hold was released, however I "practised" on another couple of QF1 flights that I could see on BA/AA but not QF and literally as soon as they went on hold they disappeared and as soon as I cancelled the hold they re-appeared (I also double checked by calling USDM to be told no space was available, then released the hold and called back and they could be seen). So I took the punt on the QF flight I wanted and it worked perfectly.
I think it might be different (seats going back to award inventory) if an actual booking was made, but the hold function of AA was perfect - you can literally make the award space appear/disappear instantly. Obviously it only works for those airlines visible on the AA tool - like Qantas.
Anyway, I have gleaned a lot on here, so just wanted to share something I discovered. For those wanting to hold an outbound leg whilst waiting for the return, this may be perfect - simply cancel the hold and re-do it within a minute might a viable alternative to the $150 change fee - albeit, only for about another 4-6 months.