Customer Support Services (CSS) for Microsoft is still receiving help requests from customers that have cloned or sold off a parts of their Active Directory forest in divestitures, or have acquired parts of split Active Directory forests in mergers and acquisitions. Cloned forests or parts of forests are not supported ways to handle mergers, acquisitions, or divestitures that involve Active Directory infrastructures. Please, see the newly renamed Active Directory Merger, Acquisition, and Divestiture: Restructuring Limitations article that explains these limitations. When you run into a situation that involves the merger, acquisition, or divestiture of an Active Directory forest, the only supported method for dealing with it is to use migration. The tool that Microsoft provides for the migration of Active Directory forests is the Active Directory Migration Tool. See ADMT Guide: Migrating and Restructuring Active Directory Domains for steps on how to handle such situations.
Kurt Hudson [MSFT]
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