Thanks, sscywong and LHR/MEL/Europe FF, for your replies - much appreciated.

Some good news. I have managed to add on the second flight (TPE to HKG) to the first booking (award). So, now both flights are on one booking, both with CX and both in J - no change to miles required, but had to pay the change fee of $175 (first ticket $150 and second ticket $25). This means I do not have to worry about bags, so that we will have more time to do lounge hops