Hi Panida,
Thank you for contacting VMware Licensing Support.
After the initial analysis, I have determined that your merge request requires further review as per our Licensing Policies.
(https://www.vmware.com/support/policies/licensingpolicies.html )
In the meantime, please ensure that the Super Users are the same across all the Accounts you wish to merge. To replace the Super User, please refer the KB article - http://kb.vmware.com/kb/2011011
You will receive a callback / email within the next 12 business hours or sooner.
Please let us know if you have any further queries.