Method to convert P2P to add Spectators?

Hi Everyone,

I currently have a half decent P2P two player listen server - client setup working.

And I now want to add to it so that people can join in the matches as simple spectators. Ie they do not need to be able to affect anything important in the game as played by the two main players.
I am using replicated variables, RPC’s, Onrep variables etc, all in Blueprints.

Would it be possible to add this Spectator functionality without completely re-doing the networking setup?
Would anyone be able to recommend a general strategy for how that might be done?