Using Amex companion voucher to OneWorld (not BA) destination

[tim.uk]

I was thinking of using an Amex 2-for-1 voucher for a trip to Seoul, but it seems that BA no longer flies there. The options presented comprise two legs, one on a OneWorld carrier (eg Cathay Pacific to Hong Kong), then BA to London. Would this work with the Amex voucher?

[NorthernLass]

Only the BA part, as a separate booking. The articles and threads on here will tell you everything you need to know about the voucher, including that it can only be used on BA, IB and EI, so you are limited to their routes.

Redemptions to HKG on BA are about to get more difficult as well!

[RK228]

Shanghai, another BA destination, is also very close to South Korea, so might be useful to keep in mind. We flew to PVG on a 241, stayed for a few days, and then used a cash ticket on KE to get to PUS (just over an hour flight time). I was impressed with KE and, although it was a reasonably priced cash ticket, they still allowed changes or cancellations for a modest fee, so not unlike an Avios booking (perhaps even better because not limited to reward availability). We ended up moving our flight 5 days earlier and it was easy to do via their website.