Add or change domains
Does your organization have multiple domain names where you do business? Perhaps you’ve acquired a new company or started doing business under a new name. If you own multiple domains, you can add them all to your Google for Work account at no extra cost. Users can then have an identity at one or more of your domains. They can share Google services as one organization. And you manage your domains from the same Admin console. You add a domain as either a separate domain or domain alias, depending on how you plan to use it.
If your users need to share files or classes outside of your domain, you can allow sharing with organizations that you trust by whitelisting trusted domains.