Imagine where by a hardware wallet is created with the set time capability to release Bitcoin for your children? I have never seen such but I think it's doable, sorry if I make this sound easy as I am not even a developer.
Some wallets support time lock, such as electrum wallet. What this means is that you can initiate a transaction and set the time you wish the transaction to be approved. This may take so long as you wish to do it and this can make bitcoin because hereditary.
Also I have seen mixin say they have a similar solution for same problem. What you think is not existing is already in existence, so there's no need to laugh at your suggestion because they aren't even weird.