It's true that the pack does not consist of one alpha and the rest being apathetic subordinates. However, in a pack of more than three dogs, the pack will generally fluctuate on a regular basis. And if we try to set into concrete our dogs' positions, we are essentially creating frustration. The beta dogs are in a continual fight for better positions and their position is always liquid, so to treat the dogs in a linear order can't be good. If one day, Dog 1 wins dominance over Dog 2, but you treat Dog 2 higher than Dog 1, there's probably going to be a scuffle that day. I dunno. The more I see the more I just don't agree with treating one dog higher over another =/

Anyhow, I really hope you find the root of the problem. But if it turns out that the dogs will always be fighting in this situation, re-homing wouldn't be a bad or irresponsible idea. I know it's a terrible idea, but I'm scared the dogs will still be fighting with one another when the baby arrives.