Does each account need a unique email address?
Solution 1:
Your account as an adult should be the main account, under which you can create sub-accounts for children. This will require only one email address.
The process is outlined in Sony's Playstation 4 User Guide.
To summarize, to create sub accounts, this is the process:
Select [Parental Controls] > [Sub Account Management] > [Create New Sub Account], and then follow the screens to create a new sub account.
You can also set parental controls there.