I believe you can do not only one job.

You can do others. Job A could be one part of Job B in broader range.

Check your background, your expertise, and your experiences to see which one is matching the requirement. If you can find one, then you may spend time to prove it by evidences. Recommendation letters from your current manager and HR of the company you are working on are helpful. If you have any publication, it will be a good evidence, too.

I believe evidence is more than words.

I have no experience on this issue. I just try to say something as I know.

Good luck.