DNSMasq conditional capability rely mostly on its tagging mechanism and it is only related to its DHCP side.
One solution would be to first use the DHCP side of DNSMasq to tag which host is "child" and which is "grownup":
# grownup network
# child network
So, conditionally set
dhcp-option to attribute a specific DNS resolving chain to "grownup" hosts (assuming
10.10.10.2 are your DNS servers and
192.168.1.2 is your DNSMasq box IP address):
From there, "grownup" host will directly resolv through your ISP DNS and the "child" ones would use DNSMasq resolving chain (or any other DNS server sitting on your DNSMasq box).
Finally adding a few
host-record or a
For more about about DNSMasq: