How do I purchase rainbow stars as Adult and move to my 7 year old?

I see a lot of misinformation here. Related to xbox, I have 2 kids who love to play. So if you buy something like the Deluxe version, then all accounts that share your xbox gold with you will get the perks, such as the deluxe costumes and what not. Rainbow stars and currency however are different. You cannot buy Rainbow Stars in game through EA with a child account on XBOX but you can easily go to the xbox store on your xbox (using your childs account) and by them there. Only the account used to purchase it will get them. What I do is I go and add money to my kids accounts on occasion. It puts it on thier accounts as XBOX credit. Then they can go themselves and use it to pick up what they want as long as it doesn't exceed what their account has on it. All other non-EA games let my kids use their xbox credits in-game so not sure why EA doesn't allow it. They can't use a credit card, but they can use what I've loaded on their account for them to spend.