Sorry, CX doesn't have a seniority system -- if we had a seniority system, people's careers wouldn't be stunted by some ex-Oasis schmuck that shouldn't be here in the first place. Either have a seniority system or don't -- either way is better than what we've got.
With a true seniority system, Oasis captains would be demoted to FO's. Oh, I know what you're going to say... They came here as captains, so they should get to keep that. So what??? Other airlines with a seniority system promote and demote people as necessary, why in the hell do we have to honor the mistake of a former manager for the rest of our careers? If you don't like the demotion, then you're free to leave. Nobody wants you here anyway.
Or get rid of the seniority system altogether. Guys could get upgraded on merit and experience rather than just the luck of having an early hire date. That would work, too. Just, pick a damned side one way or the other. Our union is useless!