Looking at how DitV deals with conflict, it seems to me that group conflict involving multiple players is likely to break down really fast unless the players are explicitly opposing each other, particularly if anyone is left out of the conflict entirely. Due to this, I'm probably going to run my first game of DitV for two single players separately rather than for them as a group.
All of the writing in the rulebook seems to assume you will have a group of players, and the beginning explicitly calls out: "You’ll need some players — the game works well with as few as two". What's the issue/what are the issues with running the game for a single player?
My problems with group conflicts
First, when a party joins a conflict that has already started, they don't actually get to participate.
Occasionally a character will burst into a conflict already in progress. The player doesn’t get to roll dice — you can’t join a conflict already underway as a full participant — so instead you can treat the character mechanically as an improvised thing. Incorporate her into a Raise or a See for 1d8 if she’s big, 2d6 if she’s excellent, 2d8 if she’s big and excellent, 1d6 if she’s normal, or 1d4 if she’s crap. If you have a Relationship with her, that’s like a belonging written on your character sheet: roll your Relationship dice instead, no matter how excellent, big or crap she might be.
So if Brother John gets into a fight with my sister Martha, and I come down from upstairs upon hearing it turn physical to intervene, it doesn't matter that I have a pile of relevant traits and am packing a firearm, and it doesn't matter that I'm a PC: the GM, as Martha's player, decides how to incorporate my character into Martha's Sees and Raises for 1d6 (we're blood so we roll that instead of the 2d6 that would be more normal) once. Not only is 1d6 almost completely irrelevant to the outcome of the fight, I don't even have control of my character's actions any more. The GM might decide I try and shoot Jon, Jon might decide he defuses the situation by shooting me, whatever. If Jon reverses my sister's blow he may well respond with "I kill your sister in front of you". If the GM takes that blow, I'm dead. This seems very contrary to the way the rules are supposed to work and can't happen with a single player.
Second, conflicts don't line up well with things happening outside of them. Whereas in e.g. Shadowrun I have an idea of how long each round of combat is, in DitV a round of combat might by half a second or several days, depending on the kind of action described. If a blow takes place over several days player characters not involved in the conflict may cause problems by interfering with the ongoing events in ways that don't tie in to mechanical resolution.
Third, in group conflicts, everyone goes in turn. Lets say I raise by running downstairs, out the door, down the street, and quickly fetching the steward from his house. This isn't entirely unreasonable to do during a fight, but definitely takes longer than another PCs raise of punching our increasingly violently angry villager in the face. Nonetheless, according to the group conflict rules, everyone gets one Go per round, regardless. My next raise might be invoking the power of three with the fetched steward and the other PC while you just deflected the punch and returned one of your own. That's weird and problematic.
Fourth, in group conflicts it's not clear what's at stake. If the players are on one side and other stuff is on the other side that sort of works, but if people are representing a wide variety of interests and takes on what should be done then it's a lot less clear what happens when someone other than the instigator wins. "The instigator doesn't get what they want" isn't a very satisfying answer, especially when whoever won was mostly but not entirely on their side.