Payroll Entry In ERPNext

I added a new field in payroll entry how can i add validation because when i click on get employee button the table generated is not getting filtered based on the new filed?

This might help, As you see the Get Employee button filters based on company, branch, department and designation.

@walstanb so should i add the employment type after the designation? but i dont want to make any changes in the .py file can you help me with the custom script?