Right after 9/11, I flew US Airways from Miami to Philadelphia several times. On one particular early morning flight, the gate agents announced that due to the extreme light load of the flight, all passengers could board at the same time. This was at a time when US Airways still offered full First Class amenities and their 757s had 24 seats in First Class. All in all, there were two Chairman's Preferred members sitting in First Class, and four passengers in Coach. There was a total of eight flight crew members onboard (2 cockpit, 6 cabin).

No, the cabin crew did not invite any of the 4 pax in Y to sit in F.