One of the basics tenants of any SLI is no leapfrogging within a list. At the constructive date of the merger a snapshot of lists is taken. Each list is then stovepiped placing each pilot in the highest paying seat their seniority will hold on a constructive basis. Those lists are then used in the actual SLI integration. DEC pilots would be slotted no differently than if they were hired as copilots. Every merger I am aware of starts with the above as the first step so DEC pilots present no obstacle.