Hey Mikeyfly,
Happy to play about with the routing to achieve the 4 1st tickets. I'll add SIN to the list of routes. I suspect though it will be a waiting game - i.e. unlikely to be any 1st redemptions available 350 days out.

Hey Cymro,
Re when I want to do this, it's 13 months away, so time on my side, just trying to plan to get the most out of this once in a lifetime trip!!
I like the ex-EU idea - challenge is that me & hubbie have the vouchers (2x 2-4-1s & 2 x GUF2s), my brother and his hubbie are the guests, so we'd probably all have to do ex-EU (not out of the question, but as my brother has MS, could be a bit too demanding for him.)
Re the HKG-TPE redemptions, I was pretty surprised, but there seems to be a large amount available when I randomly checked late next summer on the BA website.