How do I add an employee that is already associated with another employer? According to the tutorial (from the employee perspective) you can flip between employers.

Hello there, ralderson. Let me share some information on adding an employee already associated with another employer in QuickBooks Online.

We can resend and invite your employees and ensure they use a different email for this setup. To do so, here's how:

1. Go to Payroll, then Employee.
2. Select Add an employee. 
3. A prompt window will show and ask you for your employee's information. 
4. Add the details needed and ensure that the Employee self-setup is ticked so they can self-set up in Workforce. Also, they'll receive an email with instructions for setting up their account. 
5. Select Done.

For reference, you can check the Set up and invite a new employee section of this article: Invite your employees to QuickBooks Workforce to see pay stubs, W-2s, and more if you use QuickBooks Online Payroll.

Furthermore, if the issue persists, I suggest contacting our support team so they can further investigate why such thing has happened. They have the necessary tools and skills to check this. 

In addition, if you want to add your employee's updated paycheck information, you can visit this article for guidance: Add pay history to QuickBooks Online Payroll.

If you have other questions regarding adding employees to QBO, you can always get back to us by replying to this post. We're always here, ready to assist you.