Think I just found a loophole lol. You can buy 25K amazon pay vouchers using your gold charge card using your primary number.
Then you don't even need to get add-on cards, just put a different number (someone u trust cause voucher will go there) and use the same card. The payment still goes through and gets posted as Reward Multipler platform on AMEX app (points not credited yet, but if it works that's easy)