I at least got my rebookings sorted. The return SIN-FRA which was downgraded to F, they refused to rebook to SQ at the same times. Apparently SQ wouldn't release the space to them. So at my request (I'm originating in AKL), taking the other way around with United to SFO and then Lufthansa back from there to FRA.

I also had a second booking that was impacted by a shorthaul change - managed to switch from a A343 to an Allegris A359 via MUC about 12 hours later.