I had this happen with my family when a DL schedule change messed up the connection times on an international return flight. I didn't even think to check for new ticket numbers at the time. Then we arrived at the airport and AF only had the resrevation and not the ticket. It was finally fixed after a few international calls and running between the terminal where the DL desk was located (after it finally opened an hour late) and the terminal with the AF check in desk. Mom and Gramma made it to the gate with 2 minutes to spare.