Can all be done online if your cards are registered for the online service. If not, its not difficult to set up at americanexpress.co.uk

You may be able to get them into your account, as long as the surnames match. It depends how fussy they are about matching the initial as well. Nothing to lose, though.

(PS. If her card does not qualify for Membership Rewards Classic, then you won't be able to transfer. The standard Membership Rewards package does not allow transfers, only redemptions for stuff in the MR catalogue. If Classic is not included with your package, you can pay for it - £20ish, I think, per year.)