Child support...

My hubby has 4 children and 1 on the way (ours) we live in NYS he is sole provider to our household and pays child support each week, he recently got a new job and earns $500.00 each week before taxes and gets paid biweekly after taxes his bring home is about $768.00 and his boss informed him that the child support unit has submitted paperwork and wants $534.00 every pay period leaving us with $400 give or take to survive on our rent is $525 per month we also maintain vehicle and utilities obviously is this even legal? How can they leave him with less then he can survive on mind you none of his children need or want for anything and they're psycho mothers don't allow contact at all won't comply to custody hearings or anything which is a shame cause he's an amazing dad to my son! I'm just sick over here wondering how we go from getting by to well never make it and I can't get help because he makes too much money... This is outrageous!!!