Does anyone know, if I book the flights separately over the phone, does the upgrade voucher only apply to the first one? It looks like from their terms and conditions that it wouldn't be possible, even though it can apply both ways when booking a return flight for 1 person.
10. The Cabin Upgrade Voucher must be used at the point of booking a flight through the British Airways Executive Club account. It is not possible to amend an existing booking to utilise the Cabin Upgrade Voucher and nor can a Cabin Upgrade Voucher be redeemed at the airport.