Correct.

The only context in which this could be negotiated would be SLI. While not utterly impossible it is far beyond anything an arbitrator would remotely impose so it would have to be negotiated with the acquiring airline's union. I'm also guessing the company would have to approve since they're basically taking people they're not obligated to take in an SLI context.

Any why would an acquiring union even agree to bring back people who will end up senior to any of their people? Only way would be a staple.