Apple gift card on child’s device

Can you redeem a gift card on a child’s device? In short, yes, but apple support misses a crucial step in their instructions. You must also unlock account changes for their device on the family managers account, then go into their device and add a billing address. Once that’s done it will work. If you add it to the family managers account your child’s device will still charge to your card, not to the gift card. But without the billing address they can’t use the gift card either for some reason. Frustrating circle of searching to find this important piece of info. Hope this helps.