We make it in single 0 for children 5+ years and by 8 they normally take the 00 size. The liquid I make is more for babies and not strong like the cascara sagrada powder form. No one should take cascara sagrada that is not in a formula and in a capsule, but I know a few that do and they should not.
For children the fruit diet works and also if you read the Christopher colon book, they have candy formulas you can make for kids and many do this when they can't swallow capsules.