Maybe just you and EastUS....
Your post does illustrate why there will only be two lists, though. Much like the bankruptcy Judge said he didn't care about what happened to AA employees in 2003 when considering to approve AA's 1113 motions, only about today, an arbitrator won't care about mergers that happened in the past and whether to undo those seniority integrations - he'll only care about the seniority integration in a US/AA merger (IF it happens). US has an official, accepted by both the CBA and company at the time it was completed, integrated list and AA has an official list. That's what will be used.
Jim