The only “link” AF (or any airline I would guess) can make is for two PAX traveling on different PNR on the same flight (so that if the flight is overbooked for instance, both passengers would be considered to be traveling together). Useful when one paid and the other is booked through an Award ticket for instance.

Linking two bookings together so that for instance, they are aware that they need to wait a bit if your first flight is slightly delayed is, AFAIK, not possible