Adding a paid flight to a QF frequent flyer redemption booking. Is it possible?

I have a query about adding a paid/revenue flight to a QF redemption booking.

For example I want to book a reward seat from London to Hong Kong on BA, but then as there are no reward seats from Hong Kong to Sydney, I want to know whether I can get QF to add in a paid flight (it's AU$500 one way) to the reward booking so I can have my bags checked all the way to Sydney. I have added additional point redemption flights in before but never a paid/revenue flight.

Normally I wouldn't bother but as BA don't allow oneworld to oneworld through check on the one ticket it will be a pain to pickup and collect bags in Hong Kong.

Before I spend an afternoon on hold with QF I thought I would see anyone here has had experience in this at all?

Thanks in advance.