Basically, the kids get their own cards with their names on it. One of your categories get assigned to them and they will have sub-accounts inside that category which they can do anything with. For them, the view will be just like yours. For you, you’ll be able to immediately transfer money to them, just like you transfer money to any other category. Once those funds arrive they’ll have to distribute them into their categories.
Kids will be able to easily create categories for Charity, Savings, and Spending and easily (digitally) divide their funds how they wish. For example, paying 10% to Charity is much easier with digital money than with a $10 bill or even a handful of coins.
Additionally, we have a concept of sharing categories where you can temporarily share one of your Family categories with a child allowing them to spend directly from your category. Imagine giving the teenager funds to purchase some groceries on their way home from school, or access to the entertainment fund to buy tickets for the family to their school concert.
Kids who have phones will be able to activate their funds just as you do although you may choose to lock down certain categories so that it requires you to authorize spending from those categories. Kids with no phones may have their spending category locked open all the time allowing them to spend those funds at their discretion or you can go in and activate it for them when they need it.