Hi after a lot of going back and forth I have decided to buy DC 6, 4 and 2 a yumbox. I have seen some say that the kids ones are very small and not adequate / worth the investment especially for a 6 year old. For those who have them can you advise which sizes you would get for the above ages (ps 6 and 2 year old have big appetites, 4 y/o not so much