Since I'm not at home I can not give you the data table name you -
Watch this video from Ariez on how to create dummy accounts in SQL:
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There are two tables you need to open up. Just simply edit the name and add the [GS] or [GM] infront of their name.
This alone will not give the player account GM rights, you will need to change the player Status to 255 to give them full GM rights (If you need to know where, you can PM me - when I get home and look into the data table I will answer your PM with the exact location).