Forum Discussion
Add subdomain to existing federated domain with Exhange Hybrid configured
That seems like another stupid limitation of the "add domain" wizard, just use PowerShell (New-MsolDomain). Although I just tested it in one of my test tenants and I was able to add a subdomain to a federated domain just fine via the portal. So perhaps it's something specific to your setup. Anyway, just use PowerShell:
New-MsolDomain -Name sub2.domain.com -Authentication federated
All you need to do is to add the subdomain in the O365 admin center. It will automatically verify it and it will also automatically inherit the authentication settings of the primary domain. PowerShell should work just fine as well.
This part I don't understand though, can you clarify?
If I add coworkers.company.com domain from Admin portal, somehow it give permission to the user@coworkers.company.com we add on wizard user to create new Office 365 tenant.
