Converting old personal Apple Account to Managed Apple Account

We have some old colleauges, that set up their business mail account as a personal Apple Account. These accounts were created long time before we started using Apple Business Manager and claimed our company domain. If I want to create a managed Apple Account for a user, that allready created a personal Apple Account with his comany mail adress, it's not possible.

So, is there a posibillity to migrate a personal Apple Account, that is set up with a company mail adress, to a managed Apple Account?