Hi @RA_Echo & welcome 
<2.> It’s 75% perfect. A few additions needed to make it 100%
<3.> Pros: It allows the kids flexibility to see what they have in their account and what they’ve spent it on. It also allows them to use Apple/Google Pay if they have a qualifying device. The ‘managing’ parent has full control, without intruding too much. Cons: Only one ‘managing’ parent can manage at this stage. ‘Co-parent’ management has been hinted at.
<5.> The account issues a payment link (URL) which can be shared, emailed, text’ed, Whatsapp’d to anyone. When the anyone clicks on the link, it takes them to a webpage where they can enter the amount to pay (see here for an example) and select the payment method (the anyone’s card/bank account details - which can be non-Monzo) to pay directly into the U16 account.
<9.> Simple. If you’re used to the Monzo app.