Can i edit compensation of existing employee from mid of the month?

Thanks for posting in the Community, arushi-singh-pro.

If there are no automated super payments for the pay run to be modified, you can unlock and refinalise it to make changes. If a pay run has automated super payments you can create an ad hoc pay run to enter the changes needed. 

Here's how to unlock a pay run: 

1. On the Employees tab, go to Pay Runs. 
2. Select the pay run to unlock. 
3. Select Pay Run Actions and then select Unlock. 
4. Enter a Comment of why you're unlocking the pay run.
5. Select Unlock. 

Once done, you can add a different rate on an employee by adding a new earnings line. 

1. Click on the employee's name that you wish to add the earnings line. 
2. From the Actions button, select Add Earnings. 
3. This will add an earnings line which is pre-filled with the employee's primary pay category. 
4. Enter details needed for that employee's pay run. 
5. Once done, click Save. 

You'll then need to create and lodge an updated pay event to update the YTD report of the employee to the ATO.

You can check this article for more detailed steps: Updating Employee Pay Rates.

Please let me know if you need anything else. Have a nice day!