User management and 10 Azure Tenant Collaboration with a total around million users.

Hi Azure B2B Team, 

We are currently working with 9 clients and each client having 10,000 users. Now each client wants to access EXO and SPO resources with each other. We are aware that can be done one tenant inviting users of all other tenants as Guest users. Now imagine all other tenants doing the same. This is an enormous number of users to manage. 

 

Is this the only way to to this. We know this can be done but isn't there any centralized service that can do this  which can be managed centrally with much less mess. 

 

Regards,

Subodh