By default, Apple does not allow us to provide hardened security so there is no way for us to secure Boomerang against being Uninstalled by your child. By default, we notify the parent if the Boomerang App is uninstalled while connected to the internet.
Another component, the Boomerang Device Management Profile is also installed and this can also be removed by your child. The Boomerang Device Management Profile is the Apple MDM piece that governs which Apps are blocked by Age Rating and also the Scheduled Screen Time.
Workaround to achieve some security:
1. Passcode only known by you (parents)
2. Child uses fingerprint to access device
If your child is removing the Boomerang Device Management Profile, then they are prompted for the passcode for the device. This is the same passcode as the one used to unlock the device so it is known to them. The way to provide some security is to make the passcode unique and known only by parents. Then the child will not be able to remove the Boomerang Device Management Profile. To access and unlock the device, the child would use their fingerprint instead.
Notes: This workaround to achieve some security will only work on devices that have a fingerprint scanner. And there will be times such as when the device is restarted where the passcode must be entered on "first start" before the fingerprint will work. So far from a perfect solution but a step. We are hoping that Apple allows more robust security in the future.