Well, sounds like you're hanging in there and (unfortunately) rehoming might be your only option if this can't be resolved.
Having just read on another forum where the management system failed after years of success, a person was bitten, two dogs got into a fight, one dog was seized by authorities, and the other dog was euthed by the owner...I can't stress enough that you seek resolution over management. All it takes is a split second, and disaster can happen.
I'm not in favor of management in the long term, especially if the human members of the household aren't working 100% together. Baby gates, rotation, muzzling, separating, and even medication can be helpful while you're working to resolve your dog's issues. But it's not a substitute for resolving the dog's issues.
Long term management is not resolution. It's like playing russian roulett with human error being the bullet in the chamber. Frankly, I'm surprised when I hear trainers actually teaching it as a long term or primary solution to a dog's problem.