I'm shortly flying longhaul in WT. Today I noticed a good cash upgrade offer to WT+ when managing my booking online. I also see that there are CW seats available for Avios redemption on the same flight. By now it's probably clear that my question is going to be similar to the OP - is it possible to first upgrade from WT to WT+ with cash on ba.com and subsequently do an Avios upgrade from WT+ to CW? My original WT ticket is in selling class O by the way.

Any help would be greatly appreciated - thanks!