If you cannot find the Shared Parental Leave option in the adjustment leave dropdown, please follow the steps below to work around:
Go to the Leave module.
Click Setup and select Leave Type.
Select Shared Parental Leave and change the Leave Function to Others.
Click Save and navigate to Modules, and select Adjustment Leave.
Make the necessary adjustments.
Go to Setup and select Leave Type.
Select Shared Parental Leave and change the Leave Function back to MOM Shared Parental and Save.