Honey I don't know where in the Helicopter you find these things... But you need to stop having midnight conversations at the ATL airport hotel bar with Ed Bastian when he's too tipsy like that.

Also this is not at all related to the topic.

The two brands might be under one holding but this is legally a matter of sales. 074 are any EMD related to a sale done by KLM in any of their markets (US, NL, UK, etc.) and 057 by AF in any of their markets (FR, US, CH, etc) Legally, the contract was made and agreed between you and only one company so you can only ask the same company to redeem the voucher. (It's actually even a bit more complex than that but too long to explain.) Agents on the phone are able to transfer the value of the voucher to the respective company in order to execute the new sale.

You can find great info about EMD here : Link. And more specifically to AF and KL ones here : Link. (Even if published for a very specific time in aviation. Structure is the same)