Originally Posted by
navylad
You can use it in multiple legs, but you can't mix and match as you are suggestion, you can fly MLE-DXB in J vis LHR and pay for WTP and be upgraded to J, or pay for J and be upgraded to F on the flights where a F cabin is available.
i don't understand, why can't you book as one booking
LHR-DXB in CW reward booking with avios
MLE-LHR WTP reward booking with avios
Then apply one joker and one GUF to the booking to upgrade to F out and CW back?
paragraph below isn't relevant as OP would be on a BA flight from MLE not MEL
The only issue I see is on the return as at least one flight wouldn't be on BA (perhaps the OP is planning to route MEL-HKG on QF or CX) then on to BA from HKG. For this the joker and GUF would obviously only apply to the BA flights and not to the non-BA flights.
In terms of TPs and avios then you aren't entitled to any since this is an underlying reward booking. It is possible you may get a bank error in your favour but I understand BA have been working on fixing that.