How to make Payroll frequency (Or Payroll) on Payroll Details mandatory while Adding a Non-Worker

Summary:

As per client requirement, there is a need to mandate user to enter Payroll under Payroll Frequency when in Payroll Details page while adding a Non-worker.

In VBS, Payroll field is required by default, I have additionally made Payroll Details section required but seems there is no option of making sub-section- Payroll frequency as required (it is greyed out), Problem is- I am able to go to next page in flow without entering any Payroll, Any suggestions pls?

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