United I have a question. I have mileage plus credit card and I want to buy basic economy ticket. It’s my understanding that because I’m card holder I can still bring full size carry on with me. I also have United gift registry or balance I want to pay for that ticket without using my credit card. With that being said, how united know that I’m mileage plus credit card holder? Or I must use mileage plus credit card to buy that ticket instead? But then I can’t use my gift card.

if I must use cc, can I use most of my gc to pay then use cc to pay remaining balance?