This may seem like a dumb question and maybe I am overthinking this but here goes. Say a newish pilot meets the 1000 121 SIC requirements and upgrades at Mesa. Now take another FO that has been with Mesa for a few years and chooses to hold off on upgrading because of his good schedule or whatever. When he (the senior FO) decides to upgrade and if the company does not have any vacancies available, does the senior FO take the place of the guy lower on the list, and the new guy with barely 1000 hours gets displaced back to FO?