Net pay is defined as an employee's pay after deductions and withholding. If you believe you have grounds to modify the 20% order you should bring a motion to modify.
Your situation is too involved for an online answer.
Using the written documentation -like the current order - you have is a good place to begin. Contact a local lawyer - many may give you a free consultation for 30 minutes - to discuss your specifics. Far too many variables exist in the short post you wrote for any further observation by me.
You might find my Legal Guide helpful "How to Choose A Lawyer For You"
You might find my Legal Guide helpful " What Do I Tell My Lawyer"
No one can know what the record is in the case because online we cannot see your documents. You need a lawyer. Check with a lawyer in your locale to discuss more of the details.
Good luck to you.
NOTE: This observation is made available by the lawyer for educational purposes only. This observation is not like a communication with a lawyer with whom you have an attorney-client relationship along with all the privileges that relationship provides.
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