An encrypted Mac can allow multiple users to login by enabling additional users from within the Security & Privacy Control Panel. The computer needs to be bound to the Iowa Domain, so additional Authenticated Users can log on to the computer.
After the computer has been bound to the domain, an administrative user with an administrative account will need to log onto the computer.
Power on the computer that has been previously FileVaulted. If this needs to be done, please see ITS Article: Enable FileVault 2 through Casper - Article 103662
Log into the Mac with an Administrator account to unlock the FileVaulted computer.
Have the Administrator log off the computer, so the computer is at the login window, asking for a user name and password. Have the additional user(s) log onto the computer they need access to.
Once the user is logged in, open Systems Preferences. Click the Security & Privacy panel.
Click on the FileVault tab to access the FileVault settings. Click on the padlock to allow changes to be made to the FileVault settings.
Click on the “Enable Users” button.
You will see which additional network user accounts that you can enable to log into the computer and unlock the hard drive during login (this will be needed if the computer is powered off).
Click on the Enable User button next to the user you want to allow access to. The user will be prompted to enter their hawkid password that they logged into the computer with. Click “OK” to accept the password.
Once the password has been accepted, a Green Check mark will indicate that the User’s account is now permitted to unlock the FileVault upon login:
Walk through the same process to allow additional users to log onto the FileVaulted system.