@Gizmo_Ger
Just setup unbound, preferably the compiled version (the instructions don't work if you already installed unbound using apt-get)
Configure unbound to use a unique IP and port, for example IP 127.10.10.1 port 5551.
Look at the configuration example listed earlier in this topic.
After completing the configuration, restart unbound and check if the resolver responds correctly by entering:
dig @127.10.10.1 -p 5551 +dnssec www.raspberrypi.org
Now install knot-resolver, using the instructions here. Select your platform and follow the instructions under Add repository and install manually
Configure knot-resolver to use a unique IP and port, for example IP 127.10.10.2 port 5552.
Again, look at the configuration example listed earlier in this topic.
After completing the configuration, restart knot-resolver and check if the resolver responds by entering:
dig @127.10.10.2 -p 5552 +dnssec www.raspberrypi.org
Edit /etc/dnsmasq.d/01-pihole.conf and remove all server= entries.
Create a new file /etc/dnsmasq.d/04-servers.conf, content (as per provided examples):
server=127.10.10.1#5551
server=127.10.10.2#5552
restart pihole-FTL.
done...
The changes made to /etc/dnsmasq.d/01-pihole.conf will be undone by pihole -up and pihole -r, so ensure the server entries are removed from this file after upgrading or reconfiguring.