You're absolutely right Land-of-Miles - availability isn't great in I, including onwards to Australasia. I really meant 'flexible' in the same spirit as a miles booking on BA - if you need to bin it then you'll get a refund, but there's little or no chance of getting redemption availability exactly when you want it if you're just looking to reschedule.

FWIW these were leisure bookings as well - so less likelihood of a change due to, say, a meeting being moved. More likely to have been down to an (non-critical, so not insurable) illness of one of the elderly members of the clan. In which case we'd probably just have cancelled as the older they get, the longer it takes them to get over it. So, for us, the deal worked well.