Amazon question?

So I have a question that I can’t ask amazon right now because their phones help  Center is closed right now due to the corona pandemic so here’s my question I want to know about their gift cards I already have one on my account right now that I used some of it on something and I have money left over but the thing I want to buy I don’t have enough for so what I want to know is if I buy another gift card with whatever I need left for the item I want to buy and add the new gift card to my account will that be combined with the money I already have on there or will it just reset as a new gift card and will I lose whatever money I had left over on the old gift card?