Generating a demo package that can play online with full game?

This is maybe not technically an “Engine Source & GitHub” question but I’m not sure where else to put this.

I have an online multiplayer game which I’m selling on steam. For marketing purposes I also have a free “Demo” build which has most of the content ripped out. My process for creating this build at this time is this:

  1. Change the steam app ID
  2. Set bDemo to true in my game instance class, which disables buttons in the menu
  3. Go into Project Settings -> Packaging and remove non-demo maps from the inclusion list
  4. Package

This works okay for what I’ve needed so far. However, I’d really like to include a limited online mode in the demo in the near future, and since the game rarely has any concurrent players I’d really like for the full game to be able to connect to demo lobbies and vice/versa (if the demo user has the required map). It would be unfortunate for the player base to be split like this, since after purchasing the game you’d basically be unable to return to the demo and there would be far less players.

I’ve noticed however, that even if I make two identical packages they are unable to find each other in-game due to the version being different. I’m not totally sure why this happens, but I know it’s going to cause issues finding games with demo users even if the builds are functionally identical. I have to imagine there’s a way around this, can anybody point me in the right direction?