The Guide to Organized Play says a legal game consists of 4 players or 3 players with one GM run NPC.
This seems simple enough, but I can't find anything that says if those are registered players or just players. The reason I am asking this question is that I am wanting to try and put together some organized play for a local home group and may be in the situation where a couple of the players will be registered and a couple might not be.
Can I run a game with mixed registered and non-registered and the registered players still get credit for the scenario, while the others don't?