I've checked in with AA for a flight tomorrow RDU-LHR-NCE. But I can't check in and print boarding passes for the BA segment. Is this normal? BA lets me start check in but then tells me to go to the airport for boarding passes. It's technically too early but they are going with the time of the first segment. I could check again tomorrow morning with BA to be sure it was 24 hours before the BA segment. Would that make a difference?

When I do go to the airport, should I go to an AA desk to get boarding passes, or do I need to find a BA desk? I don't know if there is one at RDU.