I'm not going to outright accuse people of collusion. Because in a home game that's would justify serious ass-whoopings. However it is suspicious if several players are whispering back and forth to each other. It's shady at the very least.
Dylan and Paul had a plan prior to coming that they would share the winnings if either won. Now that in itself is not collusion. But it is close. And jumping into collusion from there would be really simple. They could easily have been folding the best hands to each other, or telling each other their hole cards.
"Team" play in a home tourney is just kind of weak, especially in a friendly game. So who knows about the OTHER two dudes he brought? They could have been colluding with each other too, which would make us some serious suckers. Not that "friendly" games shouldn't be competitive, they should... But when there is under the table dealings by "guests" (not regular players)... I must draw the line. ..
So if anyone is out there and is reading this... No team play, collusion at my home game.