Hi Manish,
Since with r12.6 and EEM 12.0.2, using EEM for authentication makes no sense as you have no way to point to multiple domains, unless there exists a trust for those domains via a forest. Alternatively, CA SiteMinder might do the trick for you.
Otherwise, please upgrade to latest SDM version (r17.1). What's preventing you from upgrading, considering r12.6 reached EOS almost 2 and half years ago?
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Kind Regards,
Brian