Dropbox controls for individually created accounts

Hi, 

The customer that I am working with has a number of users who have created "personal" Dropbox accounts.  They where created using there organisations email address i.e. @contoso.com. This was perfect shadow IT, as OneDrive wasn't rolled out at the time so the users found their own solution.

Is there a way to bring them under MCAS management or migrate them to a business Dropbox account and thus MCAS managed from there? 

I understand that the second question is probably more of a Dropbox question.  Dropbox is accounts are actively used by these accounts, so like everything in I.T the ideal solution would be invisible to the users.   

Any help or guidance is appreciated. 

Martin