Tag not monitored by Microsoft.
This might help
https://learn.microsoft.com/en-us/answers/idea/548663/merge-two-microsoft-certificate-accounts.html
Or this one that is the main topic your might looking for. There is also a description how go get support from Microsoft
https://learn.microsoft.com/en-us/learn/certifications/merge-profiles
I hope I could help you to find the next step and you succeed in merging ;-)
Best
Michael