Anyone in the room can get up to the # of meals listed on your card. If your son is under 10, your card will say 2 adults / 1 child, so anyone can get up to 2 adult meals and 1 child meal.
I often get meals for the rest of the family and carry them back to the room. Usually I have to make 2 trips because I can't carry 4 meals at once, and that's never been a problem, either.
Enjoy!