I had a hard time finding clear info on this, so hopefully this will be helpful to someone.

My wife, 1 year old daughter and I flew Papeete to Bora Bora on Air Tahiti. The guide books mentioned the various passes and we were travelling during the low season, so I decided to wait and get the tickets once we got there. We went to the Air Tahiti office in downtown Papeete (near the Marche) and took a number; there was about a ten minute wait. The agent helped with the flights and suggested that we get the family card, which would require a trip "upstairs." For some reason, I had decided not to bring my passport with me, so she held the tickets so I could return the next day and purchase them. I returned the next day and was sent to a nearby vendor to get a small picture for the card. I assume it was passport sized but I didn't check very closely. They issued the family card for 2,000 XPF. I then went back to ticket the reservation with no problem.

The family card gives adults a discount of 10, 30, or 50% depending on the flight. Apparently they are color coded somehow. We took a 1:10pm flight from PPT to BOB (via Moorea) and an 11:30am flight back and the cost was 22,900 per adult. This is a lot less than the 34,986 currently on Air Tahiti's website, but there may be better fares than that available.

This fare was to have a 10 kg baggage allowance and apparently we could have gotten 20 kg if we showed our recent international boarding passes. As it happened, they weighed our bags (just over 60 kg for the two adults) but did not say anything in PPT or BOB.

The whole process was quite easy.