Ok here is a little write up I did. I was unable to load the word version to the site so I uploaded the a zip file with the original document but attached pictures of the write up.
The only downside of this is it will only show an IP for the Synology in the pi-hole interface because the Synology uses pi-hole through a docker bridge being that it is unable to contact it through the macvlan.
Pi.zip (387.9 KB)