Bring your *G card (or possibly other proof of your number and status). At baggage check in and lounge entry, the agents will grant your benefits. I don’t think the number on an award record can be changed.

The lounge access is straightforward because their system is set up to accept a different card for access. The luggage is a little trickier so I would allow some extra time for that step and only some agents may know how to do it.