Access for multiple domain users to SQL Server using Windows Authentication We are delivering SQL Server 2012 SP1 Express edition as part of database with our application. We setup SQL Server express edition as silent installer that user can choose to install or not. 

However, I am seeing problem with windows authentication when Domain\User1 setup  SQL Server and Domain\User2 on same machine tries to connect to the same instance created by User1. Though, User2 can log in to the instance created by User1, User2 can't create database or access database created by User1. Following is the error message shown when User1 tries to access database.



I know that we can add domain users when installing SQL Server manually. However, because we should setup SQL Server as silent installer with command-line parameter, We can't add other domain users. Is there anyway that we can allow multiple domain users to connect to database while still using Windows Authentication?
For troubleshooting purposes you could fine-tune your deployment after installing SQL Express by attaching this one-liner. Feel free to get more granular with security as needed--perhaps a more exclusive user group besides the local USERS group (and DB_OWNER--hopefully is overkill and can be something much less):

sqlcmd -E -S %COMPUTERNAME%\SQLEXPRESS -Q "CREATE LOGIN [BUILTIN\USERS] FROM WINDOWS; USE &lt;your  database&gt;;CREATE USER [BUILTIN\USERS];EXEC SP_ADDROLEMEMBER DB_OWNER,[BUILTIN\USERS]"


p.s. be sure and change  to the actual database name of the local SQL Express database. And if SQLEXPRESS is not the actual instance name--change that too. There are alternate syntax variants available as you progress up the SQL 20XX versions.