This has been discussed a few times in the last few months.

I had quite a few award tickets this year for which I also showed my AZ status card - the agents at AMS never managed to update the number in the reservation. Only once - checking in with a third-party agent at ZRH - was the agent able to do so.

But may I remind you that you do not need to have your Delta number in the reservation to obtain your luggage allowance. Just make sure to have your card with you when travelling, and show it to the agent at check-in.

Note that FB award tickets come with a free bag in Europe (if you are travelling on KLM which otherwise would require payment for the first bag).