In theory what you are trying to do, though with innocent reasons, wouldn't really be allowed - as you are trying to double dip on status benefits (person 1, wife) with points earning (person 2, you). A bit like changing your frequent flier number in the air, or after you've already used the lounge... it may be possible, but can often go wrong/unchanged.

Hence, as mentioned by iknowthings, you could try - but I would be surprised if the hotel allowed. Even if they did, the bigger risk is that they change the Marriott number, but not the name on the reservation, then neither side would earn any points as they don't match.

In this case, frustratingly, you likely need to choose which you want more: The gold benefits/extra points, or the nights on your account. It seems more likely that using your wife's account, with the gold status, would be more beneficial for you as a family (it is easy to transfer points between a household at Marriott when making a points reservation).

Good luck with fixing the AMEX/Marriott status problem in the meantime.