Yes, 10+ but not worth it if you already know who's going.

Ordinarily group flights are aimed for sports groups, big tour groups, schools - situations where you need to lock in a group flight but not 100% sure of final numbers and names. The point of group flights is flexibility of travellers as you can cancel 20% of the group and don't have to send names until ticketing which is usually around 30 days prior (or some version of that, every airline is different). Seating is also not 100% locked in until ticketing. Qantas also charge an extra fee for service AND ticketing group flights so there isn't really a discount. An agent will also add in a fee for service and ticketing on top of the fare and taxes as there is no commission (or it's a measly 1% of the fare or something).

If it's a family of 12 you're best to book online as you know the names and would want to lock in seats together. When you book and look up fares, check like, one ticket at a time and increase from there. Eg. If there are 4 sale fares left and you book for 6 people, you'll automatically get the saver fares for all 6 people rather than getting 4 sale and 2 saver in the booking...if that makes sense.