Another technique could be to make use of the workgroup security file.
Access workgroup secure?
-okay so bear with me on this one:-
if you create a workgroup file, add the network logons of your users with sutitable privileges / user group memberships, leave admin as a user but with zero privileges. The reason allows anyine to logon without requirng a password - effectively what matters is how they have logged on to the network
query the grop permissions to find of the network user is a member of the specified group in the reports on open event. Youhave the userrid as how they announced / authenicated themselves to the network, but you control permissions according to the workgroup permissions.