I have 2 children by 2 now exwifes and I'm currentlly paying child support to both. 1 is 13, my daughter and my son 18 who is in college. My wages are being garnished to pay both.
My question is this, I do owe arrearages so the state of Ca. is taking the past due from my son's mother account to pay the past dues to my daughter's mother account, how do I get them to not take it out my son's mother account?
His mother has agreed to put the child support I'm paying directly into his bank account to help out as he is away at college but this is only about 10% of what I pay and the rest goes to my daughter's mother.

What type of "account" is this, who is in control of that account

Hey there Harleesdad! Wecome to AMHD! :)

First, why are you paying child support for an 18 year old in college? Unless you agreed to this at some time when the support order was entered, support as to your son has ended. So if you never agreed to support your son while he is in college and past age 18 you should have the wage assignment terminated immediately and you should have your son's mother reimburse you for the overpayment. If there are arrearages as to your son for support that ran before he turned 18 and finished high school, have any overpayment applied to those arrears.

Who do you owe the arrearages to, how much are they, and how are they being paid? More details would be helpful.