I've done the RTFF thing, and it appears the answer to this question is probably "no," but just wanted to confirm with those more experienced Avios wheeler-dealers on the board, especially when it comes to partner awards. I purchased a 1-way Premium Economy ticket on CX for SIN-HKG-SFO in July, and I have lots of Avios that I cannot use at the moment, so I wanted to see if I could use them to upgrade to the wondrous lie-flat territory that used to be my domain while employed by a big multi-national.

There is a cash option to do this, but as usual it's awfully expensive for what's likely to be bare-bones COVID service. So burning Avios would be a much better way to do it, if possible. I'm OneWorld Emerald (BA Gold for Life), but not a member of Marco Polo. Also, unlike on Singapore Air, I have occasionally gotten unsolicited upgrades to Biz when flying Cathay. So I could hope for that, but hope is not a strategy and I'd much prefer the sure thing.