Dear Kharlon, B2B/SFG on its own doesn't manage multi-factor authentication. There's a specific product born to enhance security, the IBM Secure Proxy, that can be installed and configured with it's module SEAS to grant multi-factor authentication to B2B/SFG.
Please have a look at the related documentation here (https://www.ibm.com/support/knowledgecenter/en/SS4T7T_6.0.0/com.ibm.help.seas.overview.doc/seas_user_authent_and_authrzn_steps.html) and here (https://www.ibm.com/support/knowledgecenter/en/SS4T7T_6.0.0/com.ibm.help.seas.fielddefs.doc/seas_ldap_auth_def.html).
Best regards
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Emiliano Pacelli
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