Originally Posted by
PV_Premier
...
once you get your tickets booked with AS, you can ask them for the Air France PNR and you can use that to go onto AirFrance.com and secure the seats you want.
good luck.
Don't seem to be able to book economy seats in advance at all on-line for Economy but may be a work-around using the AF android app. There is a fee for seats prior to check-in.