Fall back to ISP DNS - is it possible?

I have searched for this answer but haven't found a definitive explanation, so apologies if I'm asking a pretty dumb question.

I use Virgin Media as my ISP (UK) and they have a "Web safe" option which filters out porn, gambling etc. I like this, it's very simple and my kids are protected. However, I also want the ad-blocking of pi-hole.

Is there a way to combine them and have pi-hole as the pirmary DNS but have Virgin's filtering applied if the requested address is not on the pi-hole blocked list, or something similar?

Thanks
Richard

Use the Virgin Media DNS service as the upstream DNS resolver in Pi-hole. Any DNS query not blocked by Pi-hole will go to the Virgin Media DNS service for resolution.

OK, that makes sense. I've found the VM IPV4 DNS address in my VM router config and entered that into the IPV4 upstream DNS. But I can still access what should be restricted sites like gambling. Have restrarted browsers etc. Am I doing something wrong?

You still have the two cloudflare DNS servers selected, so some of your DNS traffic from Pi-hole is going there. If you want to use only the filtered DNS from VM, that should be the only upstream DNS server in Pi-hole.