I've had better luck using the "Identities" feature of LP to "share" passwords with my kids phones and tablets. Mobile devices have a "PIN" access feature. I've been proposing improvements to make that even better/secure, and they've acted on some. I hope that continues.
To setup your kids devices (and tablets) as separate identities: You edit the identity and then "drag" the sites you want to share with your kid's phone (or tablet) - e.g. netflix password. You also set it up to require the Master Password in order to change identities. Then you can setup the device to function without requiring entry of the master password, or for tablets and phones, setup using an easier to use (and less secure) PIN to access the LP passwords - *stored in the identity configured on the device*.
Then teach your kids to use and manage their passwords. Because it is an identity, it is automatically part of your vault, and therefore always synchronized. If the kids change the password, you still can access the new value, or if you change it, they get the new value automatically.
I think it is far more useful than trying to have multiple paid premium accounts for each child's phone and device. And it all comes as part of every premium account, so you only need one.