Using multiple people's credits on a single reservation.
As compensation for a delayed flight, each person in our family (including <11yo children; we were all on a single PNR, in case that matters) received a travel credit tied to their own FlyingBlue number. When I now go to make reservation online, it only lets me use my credit and doesn't let me use the other family members' credits. How do I make a single reservation using all our credits? (I could book each adult a separate reservation using their own account, but that doesn't work for the children; and at any rate I'd like us all to be on a single reservation.) Do I need to call?