For what it's worth, I ended up switching over to AdGuard Home ([HowTo] Running Adguard Home on OpenWrt) on OpenWrt several months ago because it made it much easier to achieve all of the KidSafe features. What I like especially regarding the switch to AGH was easy to toggle buttons to control features, block specific web services, etc.
But the best part for me was being able to filter all of the kids devices based on their MAC addresses and easily apply specific filtering features based on MAC, also that way I did not have to set static IP addresses or run multiple dnsmasq instances.
AGH is smooth like butter. 