So they wouldn't be assignments, and not in inverse order. So they're not IAs.

You need to create a new step, and figure out how to manage it in the multiple locations in both coverage ladders. And the company is still going to want the ability to go tell someone to fly as a last resort. And you're going to need to figure out how to placate the people who already benefit from the current system because as soon as you figure out how you're going to change it, they'll be on speed dial to their reps telling them what a bad person you are for even suggesting this. Well, not really, but you will be causing a rukus.