Why not just tell your DHCP server to give her the regular DNS servers? Is this situation where she wants ad blocking but still wants to use FB?

Not OP, but in my case, most of my VLANs can’t perform DNS requests to WAN. Only the pi.hole server is able to do that (and other devices in the DMZ).

Reasoning: appliances like Chromecast/Apple TV/whatever will often ignore DHCP DNS settings if it doesn’t resolve, and they’ll reach out to 8.8.8.8/8.8.4.4 directly.

Yeah, ad blocking in general is what makes the web tolerable.