I use classes for project tracking and have some employees who work exclusively on a specific project.  I ran their first payroll but did not know how to assigned their payroll expenses to the class.  Since then I found that I can assign classes to individual employees, which I did.  But I did this after running their first payroll.  

How do I attach classes to their payroll expenses for the payroll I ran previously?  

If it matters, these employees are paid by check, which I printed.

David