Everyone is paying for this merger. I agree, some more than others, but at this point all we can do is accept our individual positions and move on. EVERYONE has felt some pain with this, EVERYONE will experience changes from this. The pain your 4-5 FOs are feeling is no worse than the 4-5 year FOs after 9-11. How about a newhire at TWA? This industry is riddled with these stories. None of us had control over this. And the few that could have pushed it into a more fair integration, pushed that responsibility of on Bloch. In the end, you can make your life more miserable by complaining, or you can accept your newly fellow pilots as equals and move on from this. There are good people, and great pilots that are coming into this combined 9E. Expect changes for the better, don't fight them. There are better ways to do things than has been the status quo of 9E. This does not mean there were not good things at 9E in the past, but there are some areas and issues that could be better managed.
I can't apologize for any injustice you feel due to the ISL, I as most, had no control over it. But realize that everyone in this industry has a stagnation, bankruptcy, or merger story. A 4-5 year FO in 1999 was about halfway to upgrade. The upgrade times will go down again when the majors start hiring, until then make the best of your current situation.