I have a K class ticket on DL returning on 7/1 from CVG through CDG (6+ hrs layover on 7/2) to BUD. My schedule changed and I could now fly a day earlier. Unfortunately it is close to impossible to find a K class seat on DL from CVG to BUD so close to the departure date and before a major US holiday. Of course other classes (B,Y, etc.) may still be available but the fare difference is huge ($750+).

I considered stand-by a day early but I think I can do that only the same day. Maybe I could stand by for a different DL (AF?) flight on 7/1 and at least I can eliminate that 6+ hrs layover at CDG.

I also wondered if other airlines would take my ticket on a seats available basis. I did this freqently on US domestic flights but I am not sure if this would work for an international flight with connections.

Any ideas? Thanks!