My 12 and 6 year olds have accounts - AA/AS/DL/WN/UA/B6 with actual miles in them. Actually the 6 year old has no UA miles as I just signed him up; needed an account to credit a VA flight next month. But miles in the rest. They also have various other accounts like KE which were needed to add them as passengers so grandparents or I could redeem awards for them.

That said, it is really just my 12 year old’s AS account (as we used to credit both AA and DL flights there) and their WN accounts that have enough miles to redeem for anything useful at the moment. Certainly not saving them up as miles devalue over time. We tend to use their WN accounts first before my wife or mine. And the next international trip I redeem forwill probably include using most of the 12 year old’s AS miles. The B9 family pooling has also nice/useful.

My 12 year old did earn AS status when he was 3. That got some comments from various agents when checking in or if we needed some seat assistance at the gate (I.e, “the baby has status?” was one I remember even though he was a toddler).