Topic: HELP - Link Child NNID to Adult Account

Hi - technophobe dad query.
My son and daughter have 3DS. I created an adult Nintendo account with my date of birth.
I now want to download a game for my son on his 3DS.
I thought i was being clever by using my sons 3DS to create his NNID thinking i could link that to my adult account so i could then use his 3DS to buy and download the game from the E-shop.
I couldn't link the two because the dates of births dont match.
I then tried to add my son as part of the family group thinking i could then add his NNID, i couldnt.
All i want is to be able to download games using a credit card from his 3DS but have the requiste controls in place so he cant go crazy with my CC.
If my son has a childs NNID via his date of birth how do i link it to my adult account or do i just create a NNID on his 3DS with my details (and the same with my daughters)
If someone has the time to provide a step by step guide i would be very grateful!!

@paddy742 Unless I am mistaken, you can no longer buy eshop games directly like that. Instead, you have to visit a webpage and top-up the account there.

So even if your kid's 3DS had no parental controls on it, if they visited the eshop they would still only be able to spend what was left of the remaining balance.

I think all the fuss over linking NNIDs is redundant.