@Flyer I create users in the setupcomplete.cmd batch file. That gets executed at the end of the WinSetup process and before the first login.
You can also with the unattend.xml file define an auto admin login process for a specific user. You can set up a counter so the auto login process only executes X times then reverts to login required. This is configured in the unattend.xml file. There is also a first run section where you can do things to update the user’s current profile.
So the idea would be to have the setupcomplete.cmd file create the user with a predefined secure password, then in the unattend.xml file have this user account setup to auto login once or twice depending on what you need, then have the first run section do what is needed to the user’s profile.
One of the last steps in the unattend.xml file is to delete the setupcomplete.cmd and the unattend.xml to erase any clear text passwords that might be contained within. Finally reboot the computer.
These are just ideas on alternate ways to go about solving this problem. I agree that accounts you create before should still exist after winsetup, but M$ typically has other ideas for us.