Originally Posted by glitchy

If your spouse is also an authorized card user (which I think equates to having their own card on the account) they also get the free bag benefit without having you directly on the reservation. Getting secondary cards is easy but make sure the secondary card also has the secondary user's MP number on it, not yours.

That's relatively new (secondary cards used to have the primary user's MP number and no bag benefit) and there was a small bit of PR when they made the change. I would not trust this to work if the flight is within a few weeks and I believe the card Ts&Cs are also explicit about that. (Annoyingly I don't think there's any way to check in advance if it's all sorted out absent a phone call; I get multiply-redundant free bags (card+status) and everything I see before the actual flight still shows bag fees.)