pmg upgrade from 7 to 8

Hi All, Finally I am planning to upgrade from PMG 7 to 8. I read the https://pmg.proxmox.com/wiki/index.php/Upgrade_from_7_to_8 and saw that in a single node environment it is possible to install PMG 8 and restore the config from the existing PMG 7 node. My question is, in my setup, I have 3...