Update Azure AD Connect to include more than one forest


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Azure AD Connect supports syncing from multiple forests. It supports only one instance of Azure AD Connect syncing to Azure AD. In cases where Azure AD is already installed in one forest, the existing instance of Azure AD Connect must be updated to sync from the other forest.

  • If all identities are represented only once across both forests (that is, you haven’t made any mail-enabled contacts), then you can simply re-run the Azure AD Connect wizard, choose “Customize synchronization options,” and then on the Connect Your Directories page, enter the name of the other forest and credentials.

    The Connect your directories page.
  • If users can exist in more than one directory, and you’ll be merging the data, you'll need to uninstall Azure AD Connect and re-install it. You need to take this action because the cross-forest join rules condition can only be configured during the first install. This is done on the following page:

    The Uniquely identifying your users page.

See also

Cloud Consolidation for Teams and Skype for Business