Is this really true? I have tried this in the past and was told it was not possible. The flight crediting to an FFP and that scheme actually giving credit to the member are 2 different things. It’s not that LH gives nothing to A3 for a P class flight but that A3 puts nothing on the travellers account for it. For what you are suggesting to work, I think A3 must give up the flight in order for it to credit to UA.