Android Enterprise Managed Domain scenario with multiple domains

Hi,

i've got an on premise SMC Server (8.1.3) and configured a Android enterprise managed domain scenario. (It works fine so far, beside the problem that registering devices only work with the self service protal - why would i use an enterprise management system if i would like my users to skip registration and use the company owned device on their own purpose?)

The matter is, i've got multiple e-mail enabled (and login) domains in my active directory / exchange system. Everything works fine when i register a device on behave of user test@domaninA.com - the self service protal checks if there is a google account for this user availible, otherwise promts to create the google account test@domainA.com. now, when logging in as user test@domainB.com, the system tries to create the google account test@domainA.com, even though domainB is registerd as secondary domain with the google account. since i'm planing to use SSO for the google accounts, this will cause real problems.

Is there a way to fix this, without creating a separate customer for domains A, B, C ...?

and if not:

How to migrate registered users from customer A to customer B?

Will there be trouble, if two or more customers share the same active directory data source?

Will i need to create separate google company accounts for each domain, or could each customer be assosiated with a different domain within one google company account?

kind regards