Is overriding Payslip earnings or deductions are not allowed?

Any work around on this? Any chances on Allowance and Commission will revert back to the original value.

Kindly advice,

Thanks.

You can use the Additional Salary function to override Earnings or Deductions. Follow the documentation below:

https://docs.erpnext.com/docs/v13/user/manual/en/human-resources/additional-salary

Thanks. Can this use for deductions?

Yes, it can.