I want to manage the phone numbers of my employees myself. Is that possible?

That is possible, provided your company is also the owner of the mobile numbers in question. If that's the case, for all the numbers you want to transfer you can send an invitation in the company's name to one single email address of the company (and not to a personal email address of the employee), and do the matching yourself. This will allow you to do the management via your own personal account.