You have a few options. The ferry run Monday, Wednesday, and Friday. Sometimes it runs on Sunday so if that's a better options, call and check the schedule.

VI Airlink also has scheduled flights for $99 roundtrip (or return as they call it). Those flights are Monday, Wednesday, Friday, and Sunday. All 7 may not fit on a single flight but I think if you called them they would fly 2 trips to accommodate you. In fact, they would probably do it any day you wanted since you'll have so many people.

Fly BVI has a plane that will accommodate 7 passengers so it's worth getting a quote from them but I suspect it will be cost prohibitive.