Create additional "sub organisations"

New Contributor

Hi MS365 Tech Community,


Got a bit of a strange setup needed - I'm looking to establish an overarching tenant with multiple so-called "sub tenants" (each of our company's projects).  Our plan is to leverage Microsoft's suite of collaboration and office tools for our projects, and I am hoping that there will be a simple way to have multiple tenants talk to each other in this way.



Company -> Project A, Project B, Project C etc.


Due to requirements in place by our projects, and the different needs of each project, we would like to create separate tenants for each of them while still maintaining one login for all projects a user may be associated with.  Ideally, we wouldn't like to use guest accounts for this as it would limit the users with company accounts' ability to interact as they would be subject to the same external restrictions as guest accounts.  Also, we don't want to create entirely isolated tenants as that would cause a login/session conflict for our users (Microsoft only allows one logged in user).


Ideally, when a user is added to a project, they get a project email account and also maintain their company account.

For example, would be an overarching login for,, and so on.  The hope is that users would be able to be displayed separately when sending mail depending on which organisation they are sending the email from.


I'm unsure of the best way to accomplish this, so would appreciate some insight if possible.





PS: I'm unsure if I've explained this very well.  Please feel free to ask questions if further clarification is needed.

2 Replies
best response confirmed by GabrielTapp (New Contributor)
Not possible currently, sorry. There are some features in the work that will make parts of this possible, but overall if you use separate tenants, expect to treat them as separate organizations, each with their individual user accounts.
Thank you for the quick response.

Is it possible to have centralised billing for all of our tenants (otherwise we'll have to log in to each admin portal every billing cycle to check that it's been paid properly)?