Contacted a few weeks back regarding a cancelled flight on AB8730 TXL-LIN, which is an AB flight operated by AZ aircraft and crew, but has no AZ flight number. I hoped that this wouldn't be to much of an issue, but just got a response saying that they are not the operating carrier and that it should be routed to AZ.
I contacted AZ with the same information -- but this seems like a sticky situation and can imagine AZ's response being along the lines of "it was an AB flight with AB flight number." Any other experiences with such kinds of wet lease flight claims?