[nakomus]

Assuming that dom2 doesn’t check for something like this it should be possible to make a province with no neighbor connections and start the observer nation there.

Dominion cant spread without neighbors, can it? That way the observer would not be dominion killed and his dominion would not interfere with the other players either.

The scout units would need to be capable of teleporting if you want to be able to replace anyone who was captured.