I was the first choice for a Supervisor position at my company in a different department but my boss would not release me as I was needed on an essential business project. The project ended successfully and luckily another Supervisor position became available in that department and I was able to make the move working alongside the person they hired instead of me. Working with her was awkward as our roles were similar and we had the same title. She never seemed fully engaged in the role and I was helpless to say anything as she did not report to me, nor her team. She proved ineffectual at the role and my new boss ended up giving me all of her 9 direct reports and duties. Her role was re-imagined into one with less responsibility and no direct reports. She is now leaving the company and will be replaced. I asked my boss whether the replacement would take back some of the direct reports and duties and the response was no. Her reason is that she doesn't want to punt the team back and forth which I understand. However this job will hold the same title and pay grade as myself. I have voiced my objection to my boss with the solution that this new position be classed a group lower and report into me, so that I will have support in my role and the authority to delegate these added responsibilities. My boss does not think that is necessary and says she will "try" to have this position reduced to a lower pay grade but not report into me. She will not elevate me to a higher job title or job group. I am at the lowest job grade for managers.
In my experience, org structures are difficult to change. So I understand if she cannot elevate me to a higher job grade but that would equally mean it would be just as difficult to downgrade this replacement job as well. Either way, the replacement role does not sound like it would support me. She says that it would but without the role reporting into me, I am helpless to hold that person accountable or force them to help. This puts me in the awkward position of having to "tell" on my colleague if they won't assist, for legit and non-legit reasons.
I want to let her know without it sounding like an ultimatum that if this replacement role is posted in the same pay grade as myself, I would apply. The way she described it, it's all the things I enjoy doing without the responsibility of direct reports and hassle of the union to which 15 of my 17 reports belong.
I feel like my experience and effectiveness in the role is hindering me to be able to do the things I love because of the added responsibilities. I get along with my boss well and we work well together. This is one of the rare moments where we disagree.
Is there any advice you can give on what else I can do?