1. After helping the assassin out of a tight spot, Ezio decides to 'reward' a hireable group in his own special way. So yes, all four members at once. Either four thieves, four mercenaries or four courtesans.
OR (and this one's something)
2. Ezio and La Volpe have a footrace, only for it to end in a tie. They come across a group of four thieves and decide to settle the tie like gentlemen with a different kind of race. La Volpe grabs two and Ezio grabs two and whichever of them gets their pair off first is the winner.
Ezio / Four or...
1. After helping the assassin out of a tight spot, Ezio decides to 'reward' a hireable group in his own special way. So yes, all four members at once. Either four thieves, four mercenaries or four courtesans.
OR (and this one's something)
2. Ezio and La Volpe have a footrace, only for it to end in a tie. They come across a group of four thieves and decide to settle the tie like gentlemen with a different kind of race. La Volpe grabs two and Ezio grabs two and whichever of them gets their pair off first is the winner.