You should have told him it goes all the way down and his balls have to go in too to hold it in place...

Never forget that family court Judges seem to come from the bottom 10%ers of the legal profession and many in CPS, Child Support Enforcement, etc.. .are the barely employable. Basic math is beyond their intellectual capabilities.

We had exactly the same experience that you did though for us it was from the non resident CP position.  DW had left SpermLand just after HS graduation and after SS turned 1yo.  A few months before had been the paternity hearing where the SpermIdiot was confirmed for paternity, CS was set at a whopping $110/mo and full physical and legal custody for my DW was confirmed by the court.  A year later a few days after our wedding and a few days before SS's 2nd Bday we finally got to court to defend the SpermClans attempt to take custody.  The courts subpoenaed tons of information. Tax returns, income information for DW, me, etc... and all of the same things for the SpermIdiot.  We came with file boxes full of information, they came with two weeks worth of pay stubs.  Our attorney hammered repeatedly on them and the Judge for failing to fulfill the court demand's for information.  The bottom 10%er of the legal profession robed dumb-ass ignored all of that.  We won but it was clear that the robed idiot was pissed off that he could not deliver on his clear bias in favor of the resident side of the court action.  The most notable point where his irritation on not being able to hand him it all on a silver platter was when they motioned for my income to be considered in calculating CS.  In SpermLand SParent income cannot be considered in CS calculation. However, they have an option for a robed dipshit to apply an income reduction credit to reduce the maximum CS an NCP is subjected to.  The bitter beer face that the robed moron had when he spouted "Step Parent income cannot be considered in calculating CS. However, due to Step Dad's significant income I am applying the maximum income reduction credit allowable as bio dad should not be punished by having to provide an artificial standard of living for this child."  No bit deal. The maximum income reduction of $1000/mo only reduces max possible CS by $50/mo.  So nothing that is materially significant either for them or for us.  Though we won resoundingly in that action/hearing, that that POS benefited a micro-cent from my income chapped my ass beyond measure.

The Judge ordered CS to go from $110/mo to $133/mo, full physical and legal was upheld for my DW, and visitation was set at 7wks/yr (5wks summer, 1wk winter, 1wk spring).  SpermGrandPa's only comment that whole hearing was "Jesus Christ!" when CS was raised from $110/mo to $133/mo.  We did not know it at that time but SpermGrandMa had being paying the SpermIdiot's CS which pissed her DH/SPermGrandPa off to no end. As it came out over the years, they paid his CS for SS the whole 16yrs of the CO. They also paid the CS to the the other two baby mamas as well.  

After 8hrs in court that day the first Judge preceded his order with "I hope  you all feel better. Now I am going to do what I always do."  We wasted a day, shit tons of $$$ all for a dumb-ass in an idiot Harry Potter robe slinging a Fisher-Price wooden toddlers hammer to not listen to or hear a thing we said, spent countless hours compiling, etc....  Unfortunately idiots in robes have no accountability to actually do their job or have a brain.  Suing an idiot Judge can't happen as far as I understand.

9 years later after my DW had enough of the toxic manipulations and I had been RIFd in an industry downturn so my income was $zero DW filed for an amendment of CS.  She filed for CS review with the DA. It  Very similar to the defense of their custody attempt.  We took shit tons of info, they brought two pay stubs.  The lead up was interesting. The SpermIdiot repeatedly refused service to provide the stipulated information demanded by the DA who administrates CS reviews in SpermLand.  We provided boxes of info.  The SpermIdiot even physically ran from the Constable during an attempt by the Constable to serve him.  In response the DA contacted my DW to provide as much information as she could on the SpermIdiot's income, employer, residence, assets, etc....

She went CPA on his ass and went above and beyond providing everything the DA asked that she could determine, add a bunch of other stuff including the income assessment for licensed plumbers in the county the SpermIdiot worked in recommending the mid pay rate as a fair income for CS calculation.  Because the SpermIdiot failed to respond the DA increased CS from $133/mo to $785/mo and ordered direct payroll withholding of CS from the SpermIdiot's pay checks.  When he got his first $0.00 pay check due to the first direct withholding of CS he came screaming into to court to schedule a CS review hearing.  

As was the case 9 years before, when we had the CS review via a telephone hearing with an admin law Judge they came with nothing but two paystubs.  None of the subpoenaed information other than that. No living expenses, no utility costs, car payments, etc... This time, DW had already provided a shit ton of info including the he lived in a rental property owned by SpermGrandHag and SpermGrandPa, drove their hand me down cars, that they paid his CS on SS proven by a statement by the CSE office that he was not the one dropping off the CS payments for forwarding to DW.  As the hearing unfolded we picked them apart.  SpermIdiot could not say how much his rent was and under pressure by DW and the Judge he admitted he paid no rent. He admitted that SpermGrandHag paid his CS for SS and for his other three. That SpermGrandHag gave him cars, raised his three younger kids, etc, etc, etc... Eventually SpermGrandHag blew her stack with "What difference does it make who pays the CS, or the rent...".  They repeated their attempt to get my income considered for CS calculation.  When they made that motion we responded by reminding them and the new Judge that SpermLand excludes SParent income from CS calculation and counter motioned that due to the significant income to SpermIdiot provided by his mommy and daddy that SpermGrandMa's and SpermGrandPa's income be added to SpermIdiot's for CS calculation purposes.   SpermGrandHag lost her F'n mind. The only sound SpermGrandPa made that whole hearing was at that point. "Jesus Christ!".  Apparently his vocabulary had not improved in the 9yrs between court actions.  It got even more explosive when the Judge announced that she would take our motion to include the SpermGP's income in CS calculation under consideration.

I particularly enjoyed that moment.

I had been told at the beginning of the hearing that as the StepDad that I was not a party to the case. Which the robed idiot in the first hearing 9+ years before also said.  The difference in the second hearing was that it was a telephone hearing so my participation was not visible.  We had it on speaker phone so I could hear it all. I kept my headset muted so I could hear it all while I was pulling information out of the files highlighting response information for DW, adding arrow stickers for reference points, etc...

The telephone hearing occurred while SS was in SpermLand for summer visitation when he was about 10yo.  When the Hag lost her mind over our presentation of proof that SpermIdiot had no living expenses, that they paid all of his CS costs, visitation travel costs for SS, you could hear SS and his three younger half sibs in the the room.  I pointed out to DW that the Hag and SpermGrandPa were not parties to the case if I was not and that they should not have the kids in the room hearing all of the crap.  DW's eyes bugged out when she recognized my point.  She leveraged her position of commonality with the judge as a highly educated professional women and pointed out that the GPs were not a party to the case and could not participate as had already been ordered in reference to me. And... that they had the kids present in the room for the hearing. Her honor lost her ever loving shit on them over that part.

To end the long CS review hearing story, the Judge considered but declined to apply SpermGP income for CS calculation.  She lowered the increased CS from $785/mo to $385/mo but held the $785/mo for 2yrs due to the SpermIdiots repeated refusal to respond to subpoena and for running from the Constable who was attempting to serve him.  The Judge also upheld that SpermIdiot was on the hook for paying for after school care for SS until he was 12yo and for providing health insurance for SS. Something he had been ordered to do but never had.  Because he did not provide health insurance as ordered his share of health insurance for SS was added to his CS 9yrs earlier.  The same was ordered by the second Judge.   Interestingly he attempted to get CS lowered several months later when he came in for a CS review because he had finally gotten all of his kids on insurance.  The judge ruled that due to the lack of quality of his insurance that he had to both keep SS on his insurance and continue to pay his share of us providing SS with insurance. As a final jab in his ass she ordered that because he attempted to reduce CS less than 2yrs after the most recent order without a significant change of circumstance that he could not seek a CS reduction from her insurance review date.

Part of the Judge's order was that either party had to notify the CSE on SS's 12th B-day so after school care could be removed from the CS direct payroll withholding.   For damned sure DW did not make that call. Not our problem. They never did either.  Again, not our problem. So they paid an extra $300/yr for 6 years.  Not surprising that they did not make the call. It was abundantly clear the entire 16+ years we lived under the CO that they never even read the order.

Judges for some reason rarely exhibit brain activity in family law cases. Far too often they award CP status to people who have no business being a CP, they  far too often victimize the parent that has the ability to support and likely parent the child  far more successfully .  Our first Judge was useless and a total moron. Our second Judge was far better able to assess all elements of the situation and apply sound Judgment.

I am sorry that your experience has been polluted by what appears to be an idiot judge and system.

How long does CS go ?  Does SS gas to be inrolled in college to get support. ?   
'That's how steplife goes  These kids just collect support until they are 25 if going to college.  2

Over the past 15, 16 years most states have welcomed BM's request to continue CS beyond emancipation age IF the child is attending college or Tech school.

It may be worth asking a lawyer in case you need to be prepared. 

I dont understand why are they charging your husband $65/month for having SS18 on your benefits?

My separation agreement states that my ex and I share any out of pocket premiums for benefits.

Did the judge get the order backwards... It feels like bio mom should be paying toward the benefit not the person having the benefit paying an additional amount. Also why is he covered after 18..because he's in school still?