Ok, i've now booked flights.
After another hour playing around with the FB system, not really getting the flights i wanted, i finally called the FB hotline again.
This time a very friendly french mail attendant.
After about 15 minutes worth of searching, i finally got the following:
FRA-CDG-LAX, direct.
Outbound is in business class as all else was booked.
Return is economy. All were booked with skyteam redemption rate, so only 70K total per passenger.
thanks all for your help in this!