Cannot find a way to add an Administrator account (or, for example, Company Administrator group) into Site Collection Administrators list for each of Personal (i.e. My) Sites at SharePoint Online instance. This should be done by script ore once in the Administration portal.
Despite all tries, the only thing I've managed to do is adding such Administrator with 'Read' permissions - it is not what I want.
- PowerShell for SharePoint Online is not powerful enough to carry this out.
- CSOM model seems to have ability of changing the owner/permissions list for the Personal site, but it ends up with 'Access denied', because the only man who is in Site Collection Administrators list is the person who's site is (and the script should be ran under the Administrator credentials).