I can't speak to what's accepted industry practice when promoters hype their shows, but from an accounting perspective Moustacha has a point ... no CPA would book group sales in the same revenue category as individual pre-sales until all contingencies in the group sale contract have lapsed.
From a GM/producing end, it's absolutely true that unpaid group sales are reported in their own area in wraps but NOT in the actual advance number. They're not considered real money until they're paid, but they're certainly relevant to other decisions about promoting the show. So sure, they've shared the $10M number with the press with caveats, but internally those pending groups won't be real money yet.
Okay, so I have another question about the group sales. I'm just curious. I saw Hamilton twice at the Public and loved it. As I was watching, I thought it would be wonderful for school groups (junior high and high school). So I assumed that a large part of the group sales would be to schools. But someone else said that schools would not be purchasing tickets now for the next school year. Assuming that's true, what other groups would this be? People from the suburbs who come in for matinee day? I don't really see Hamilton appealing right off the bat to that constituency. Would scalpers and resellers buy tickets in groups?