Connecting G Suite with Azure AD - in a strange way

I wanted to combine G Suite with an existing Microsoft 365 Tenant. Due to License Constraints we were only allowed to use Microsot 365 for a limited number of persons, so we decided to use G Suite for the rest. So this was the plan:

  • Don't limit the Microsoft 365 services for everyone who is eligible to get such an account
  • Give everyone, including the above mentioned Microsoft Users, the ability to use the Google Service (additionally)
  • Have ONE single system to set up User Accounts for both services
  • give everyone access to an email box with Google OR Exchange Online
  • Use SSO for existing third party applications

The problem is that this would require Azure AD entities with a verified domain but hosting emails of this domain on Google Servers which is not normally intended. The solution I came up with was this:

  1. Enter the additional Google users as Azure AD Entities but don't assign a Microsoft 365 licence
  2. Give these persons a different subdomain, like cloud.example.com instead of eample.com
  3. Verify both domains for Google AND Microsoft
  4. Link Azure AD and Google by following these steps
  5. Now generate the additional users in Azure AD as UPN@cloud.example.com
  6. Set MX DNS entries to point to Microsoft 365 for both subdomains
  7. Follow these steps to forward incoming emails to the Google inbox for the subdomain cloud.example.com

I hope I'll remember this in the future if I need to change something in this process :/