My, my, my the lack of understanding about representation issues is downright amazing at times....
Who has more F/A's absolutely is the issue.
If more than 35% of the employees in a merged company are represented, a representation election is more or less automatic.
In the AA-TW transaction, the TW employees didn't come close to the 35% threshold. In an AMR-LCC transaction, AA's unions easily outnumber LCC's. AA could probably lay off 30% of their employees and still outnumber LCC.
Without a doubt, representation elections would be held before seniority was addressed, and assuming AA's employees decided to stick with their incumbents, it wouldn't matter what LCC's union's policies are.