To get the non-interesting stuff out of the way first: while €7.99 is just acceptable for myself, for many children that's already a big chunk of their pocket money...
As per features (the interesting bit), it would be good if children's accounts have the same features as grown-ups' accounts, but even better if I as a parent had control as to how much of that I want to enable. For example, if they think they need two MasterCards and a Maestro card each, I'd want them to have to explain it to me first.
I could imagine that account features (within the overall limits) would need to be enabled by me before they can use them, and that I can also choose how much insight I want to retain into their account activity. The older they get, the more I could then leave them free reign.
There could be some special settings that I can change in their accounts (and that they can see, but not change), like
- I want notifications about incoming/outgoing (yes/no)
- I want notifications for transactions above certain amount
- Transactions above certain amount need my approval
- Notifications for incoming from unknown sources or outgoing to unknown recipients
- Allow card ordering MasterCard (yes/no)
- Allow card ordering Maestro (yes/no)
- Notify when cards are ordered (yes/no)
It would also be good to be able to associate both parents and decide which of them has these controls, or both together.
After observing account usage and with them getting older, I would expect to move from requiring approval for their transactions to requiring just notification to finally just switching off all parental controls.
Everything else I can imagine are just already existing features, like connecting accounts, sharing bills etc.