They promoted someone else and asked me to train them on the work

I learned that I did not get the supervisor role at 10 a.m. By 3 p.m., my manager asked whether I could build the new supervisor's training plan.

The person they hired is external. I have not met her, and I have no reason to assume she is unqualified. My frustration is with the sequence, not with her.

I have worked on this team for four years. During the vacancy, I coordinated the weekly schedule, handled escalated customer cases, and ran two staff meetings when our director was away. I applied because the temporary responsibilities had made me want the actual job.

The feedback was that I interviewed well but needed “broader leadership exposure.” The director said the successful candidate had managed a larger team. That is disappointing, but it is at least a reason I can understand.

Then he said my operational knowledge would be essential to getting her up to speed. He wants me to document the workflows, create a thirty-day training calendar, sit in on her first round of one-to-ones, and remain available for questions. He described this as a chance to demonstrate leadership.

I asked whether the training work would replace any of my current responsibilities. He said we would all need to stretch for a few weeks. I asked whether designing and delivering the plan could be recognized as a temporary lead assignment. He said formalizing it would make the transition unnecessarily complicated.

That answer changed how the request felt. Training a new manager is not beneath me. Refusing every task after a disappointment would be childish and unfair to the incoming person. But I am being asked to supply the leadership they said I had not demonstrated, without the title, decision rights, or relief from my existing workload.

There is also a practical risk in doing the job too well. If I quietly transfer every relationship and rescue every early mistake, the transition will look easy. My own contribution will disappear into her successful start. If I hold back, I harm the team and prove the company right not to trust me.

I am considering offering a narrower handoff: written process documents, introductions to key partners, and two scheduled question sessions. I would decline to design her management plan or join her employee one-to-ones. Those parts seem like the director's responsibility and could put everyone in an awkward position.

I also want a separate development conversation with specific examples of the leadership exposure I lack and an assignment that would genuinely build it. “Train the person we selected instead” is not a development plan.

What is a fair level of cooperation here? How would you support the new supervisor without volunteering to perform the unrecognized version of the job you were denied?