When I disengaged, I told my DH and his Spawn together.  My situation was different in the fact that Spawn lived with us full time and I was the one raising her while my DH kept his head shoved firmly in the sand and pretended to be the “good guy”.  After I disengaged my life became a whole lot easier, while DHs got vastly more complicated.  He did everything he could to force me back into raising his child to no avail.  It wasn’t long after that he allowed Spawn to move in with her maternal grandmother.

Good luck with your decision.

Disengaging really helped me and likely our marriage.  I did NOT tell DH I was disengaging, he would have reacted very poorly to this - known from the multitude of conversations we had about the SDs and their behavior and how he reacted to me actually trying to "parent" instead of just being a support to him and providing fun things and food. Uh, no.

And I didn't disengage all at once. It was one thing at a time. What really was effecting me when I first started disengagement was planning fun things to do for all of us. Invariably, those plans would be cancelled, delayed, derided, made fun of, arrived late to/left early, etc. even if I had paid for it. So that was one of the first things I cut out - I cold turkey stopped planning things, told DH if he seemed interested in doing something, "Sure, go ahead and arrange it and let me know!"

(really the very first thing I cut out was closing his car door in the parking lot because OSDthen10 would constantly leave it open and run to the house, assuming someone would do it for her - one rainy day I saw it had been open all night and went to close it...and stopped and thought - no, HE has do deal with this - his car wouldn't start and the seat was all wet and that never happened again)

Then I moved on to the next thing that was detrimentally effecting me, such as making their lunches. Again, a no-win whatever I did. So I told DH, I've tried this, that, the other thing, and I'm blamed - so now, I am not doing it any longer. You can help them deal with it. He did so for a little while, got sick of it, then made them do it themselves which they were fully capable of.

And so on.

To this day, with YSD18, I don't really do much of anything unless DH really truly needs help and asks me. Right now the kitchen is a disaster because neither he nor YSD has emptied the dishwasher (which I finished loading and ran yesterday afternoon, after making bread) so all the lunch stuff, dinner things, and breakfast things are all over the place. I am not touching it because he or she is fully capable of doing so. I am not the maid.

I think it's counter productive to announce disengagement.. the grand flounce of "I will not care".

Unfortunately, it's a concept that I think is very misunderstood by bio parents.  They hear disengagement.. and the knee jerk reaction is "you hate my kid".

The reality is that in some cases that may be partially true.. but often because the bio parent has made the child into a person that is not likable.  BUT.. it's often that as a stepparent.. we cared.. but every time we tried to constructively help.. we were undermined and punished for our "intrusion into something not our business".  So, by disengaging.. we basically let go of the rope.. what the parent does.. what the child does no longer becomes "personal" to us... we allow them to exist in a somewhat tandem orbit.. and we come to a place of acceptance that our input is not valued.. or asked for.. and that they will do what they will do.

Of course, when the safety and sanctity of our home, our pets ourselves is in danger.. we can still step in to prevent bad things from happening... but absent that.. it becomes no longer our circus.

I also feel like disengagement doesn't relieve us of the duty to be civil and kind.. and it also may still mean we do things for our step kids.. when they are part of the household.. like when we cook a meal for the whole family (but not doing individual special requests).. or doing a favor to pick skid up from practice when a bio parent's work meeting is running long.  What we don't do is get wrapped around the axle when the kid brings home a bad report card... or forgets to take out the trash.. and if they ignore us.. well.. we can model good behavior and say a hello.. but no need to push further to try to have a conversation.

YSSnow56 was an energetic, witty boy with lots of charisma, still is.  He is DH's fave tho DH would never admit it.  Everything he did was great, according to DH, and YSS was, in many ways, a boy a dad could be proud of.  He excelled in year round sports culminating in a stellar high school football career.  On the downside, he was sometimes verbally cruel to others, disregarded my authority altho he was living with us full time and had frequent disciplinary issues at school.

After numerous trips to school to get him reinstated and after DH and YSS laughing off all issues, I disengaged.  I didn't say anything, just stopped doing for YSS.  DH had to go to the next school incident, wasn't happy about it and that was the last one.  He also got to drive YSS to the many practices and games til YSS could drive.

I felt a big relief but also felt sad cuz I felt I could have taught SD many social graces if he'd been receptive, which he wasn't.  I could forsee a good future for him but I suppose he picked it up along the way without my help cuz hes a very successful salesman.

I'd say all 3 of us, me, DH and YSS, felt a sense of relief.  DH wanted to do things his way and YSS didn't want to listen to me.   

My DH misunderstood it so I recommend just backing off what you do and become utter incompetent to solve any problems for SS and more importantly DH.  Practice those casual responses, you will need them as DH will still ask for your opinions.  Don't bite, remember it doesn't serve you to participate in those types of discussions. Shrugg your shoulders, " I dont know " and every form of that statement will be your response.  
 

Who knows what DH will do when fully stuck with SS.  He needs to feel the full force of his lackluster parenting.   Step back and let him.  

Keep in mind, I was dumb and overly involved - your classic doormat. The first disengagement was from YSD, when she was an older teen living with us. I didn't announce it, just picked up a second job and wasn't home much. I hoped this would force DH to deal with YSD more, which it did, and gave me a break from her crazy. She basically ran away at nineteen by moving out while we were both at work, and it was my DH who decided we were done with her. It was a looong five years of 90% me grappling with her mental health issues, educational issues, and constant lying; the last six months were all on DH, and he received a surfeit of her BPD and fantasy weaving lies.

When I disengaged from OSD several years later, I did it in a blaze of glory, which was a big mistake. She's a mean narc who kept draining us financially, and would make passive aggressive comments to me even as I was doing favors for her. It was as if no one else in DH's family was willing to see what a rude, selfish, entitled, socially awkward B she is, and when I finally hit the wall I told everyone exactly why. I'm sure the inlaws got tired of me complaining about OSD, and it made me the problem rather than her. I was the one with the issue, I was the one derailing things by no longer kissing everyone's butt, and I was the one no longer expending emotional labor to keep OSD happy. Eventually it led to me cutting off my in laws as well, because they kept pressuring me to get back with the program, and when I didn't, they went to war against me. So ideally it's best to just slowly fade back, redirect kids to their bio parent, and gradually become uninvolved.

I basically told DH I would let him handle things (hygiene, meals, cleaning up after the skids, laundry...). I made plans on skid weekends, even if they were just for myself. I even bit my tongue and said nothing to DH about messes and let him discover things himself. Damn near bit a hole in my tongue saying nothing about the leaky styrofoam cup slowly dripping pop down the side of the entertainment center onto the carpet, but that was the proverbial straw that broke the camel's back and Death of the Disney Dad began.

I HATE a dirty house, so I used to run after the filthy ferals and clean everything. DH was such a Disney dad that the SKs weren't required to do ANYTHING. They were absolute pigs and created a shambles every time they were at the house. We had them more than half time and DH had this thing where he needed to see them every stinkin' day so they created havoc in the house every single day with no expectations in sight. I gave up fighting with DH. When they hit late teens, I went on strike. I said nothing. No warning. Just did it. 

It just about killed me because I like a spic and span house. I had tactics. It wasn't as simple as not doing anything anymore. I used only the ensuite and then locked the master bedroom door so the ferals couldn't use it. DDstb24 was little, so I had her use only the ensuite. I was quite blatant about that. I would just instruct her to use only the ensuite for the time being and not say why. Then, for supper, I would wash only the dishes I needed to make and feed DD supper. Then, I'd leave them dirty so that every single dish, pan and utensil in the house was dirty. Then, the garbage cans were full and overflowing. SD had this thing about wrapping her period pads in a fancy origami bow with torn toilet paper. It was sickening. Well, the main bathroom garbage can was so overflowing with used pads from three periods and make-ups wipes etc, that everything toppled out across the main bathroom floor. In the mean time, the ensuite ws sparkling. Then flies were sticking to the computer stations with SS' fifity baby yogurt cups. I had stopped paying for any and all groceries because I used to shop caselots and get tons of shit in the house to stock up only to see SS binge eat and demolish 40$ worth of granola bars in one sitting and leave all the wrappers sitting there despite having gotten up fifity times to go get another granola bar. I also saw 30 baby yogurt containers, from SS binging on those and getting up to go get another spoon for each yogurt he took. The computer station that DH built had flies landing on it and unable to get off because they stuck to the station. Then the kitchen got ants from spilled juice that was never wiped up. SS dropped his laundry in the basement by the washer and it sat there for nine months and when DH got mad, he kicked the pile of laundry and a ton of spiders came running out. Oh well, not my problem.

I could go on and on, but I won't. You get the picture. The house was disgusting. It stunk. I realized that that's what I needed to happen for DH to see exactly how much I was doing to keep the house as spotless as it was. 

I never said a word. I just let the house become utterly disgusting and I let DH get more and more depressed. One day he said how depressed he was over the condition of the house. I simply said in an ever so cheery voice, "oh, well it's not my turn," and turned on my heel and walked out. I would take DD out of the house on way more outings to keep her out of the pigsty. 

One day, I came home to the bleach aroma. I walked in and the place was a sparkling palace. DH was yelling at SS to do his laundry and that things are going to change around here. Yeah, right. The only thing that changed was that the SK had to start doing their own laundry at age 19 and 21, but DH ended up taking over all of the cleaning and I did jack shit until they finally moved out. LOL The ferals are now 32 and 34 and to this day, DH remembers to thank me and show appreciation for everything I do in the house. LOL 

Oh, I also remember that at the time, DH went through a profound depression over how the ferals were so lazy and entitled. 

Here is where it's funny. As adults I like to hold family dinners. Food is my thing, so I host them. Well, SS was doing something in the kitchen and SD decided to do something too. Afterwards, I heard them fighting over making sure Evil's kitchen was spotless because "you know how much Evil values a clean kitchen and she always provided that for us." I just about cried. I giggled to my self a little bit too. LOL Now, both are always either bringing dishes or money to chip in so that it's not all on me. 

It was something I had to work out with myself. I also felt DH would not get it. And he didn't because after the last incident where  I ended all contact with his kids, we started therapy. THAT is when he finally got on board with my disengagement. Or at least accpeted it.

Disengagement is about YOU. Not your SKs or your DH. It's a technique to protect self so no need to announce. Trust me, they'll get it soon enough.

If I was a proponant of disengagement, I would not tell the. Just do it.

But... do not tolerate shit behavior from the spawn or your partner.  Disengagement IMHO should not mean ignoring crap behavior, disrespect toward you, disrespect towards your home, or towards your property, etc...

IMHO an effective way to deal with the usual blended family crap is to go full confrontation while modeling total and complete boredom with their drama.  Keep them the hell away from you, when they fail to comply with the standards of behavior and standards of performance that you demand, deliver an escalating state of abject misery. Take away any benefit that they get from being toxic.  Make it hurt.

Good luck.

No conversation about disengagement (I just "disappeared" all day during his parenting times then re-appeared for bedtime and went straight to sleep) because I had already had MULTIPLE conversations about having some basic reasonable rules and structure for his kids in my home - to which he acted like I was military style torturing the ops. 

Once I refused to be involved with him and very minimal involvement with his kids every weekend....he noticed and started retaliating by arguing with me and yelling at me about any and everything and admitting he pulled back emotionally when he noticed I wasn't as involved with his ferals as he wanted.....mind you after all this emotional trauma he put me through dealing with his endless construction grade baggage - he still expected seggs (*barf*)
 

I ended up leaving him.
 

Because him repeatedly allowing his manipulative breeder and no-home-training, no empathy ferals to disturb my peace in my home was a hill I was willing to end the relationship on. 
 

Oh well! 
 

Good luck to him finding some unsuspecting woman who can accept those unreasonable expectations and deal with his sh*tshow no-boundary Disneyland parenting 

Actions speak louder than words. I disengaged a few years ago from SD13. It started with me deferring everything to DH. Just a simple, "go ask your Dad." Around the same time we had DS3 and I had my hands full with a newborn. I stopped caring what everyone else thought what I *should* and shouldn't be doing as a SM. I stopped giving my opinions and advice. I stopped asking DH what was the latest with BM. Unless it DIRECTLY affected me, I stopped saying anything in relation to SD13. 

New habits were formed and eventually this became the new norm. SD13 has stopped asking me for rides, and automatically goes to DH for everything now. BM has left me alone. And DH has stopped bringing SD13 up in conversation because he doesn't want to hear my honest opinion. 

Disengaging has saved my mental health and I would encourage you to do the same if able!

You are about 5yrs from a watershed opportunity. For us, that was SS-31's 18th Bday.  He graduated from HS at 17.  His survival to get to HS graduation was a closely run thing.  One or the other of his mom and I were nearly always ready to strangle him. When the strangler was reachign for his throat, the other of us was willing to give him just one more second, minute, hour, day....  So, he made it to graduation and even managed that with honors.

The summer following graduation he was on our dime.  Though we gave him a decent amount of cash for graduation, we told him that if he was with us we would pay but if he was in SpermLand for his final COd visitation and let them take  his money or guilt  him into paying, that was on him.  If he was traveling with friends, that was on him.  He finished the summer with most of the money we gave him for graduation.

He turned 18 at the end of the summer after HS graduation. The next day, he was our live in beck and call chore bitch.  We had guided, cajoled, pushed, begged, etc... for him to apply to Universities and we made it clear that he cold attend any university or college on the planet he wanted to on our dime. The mom and dad full meal deal scholarship.

Nope, he was not ready.  He ventually sat  us down and told us that he would eventually finish an undergraduate degree, that he knew it was important, but that he was not ready to put in the focus and effort.  He made it clear that it would be a waste of our money and his time.  We were disappointed, but meanwhile back at the ranch and nearly 14 years later, I am in hindsight very proud that he was that self aware and ultimately confident enough in himself and our relationship as a family to tell us that.

So, we adjusted our model with him. Be a full time student, or work full time, or half time work & half time school and he could live at home on our dime.  Nope, Not interested in work either.

So, it was time for  him to be our 24/7 live in beck and call housekeeper, chef, laundry service, etc, etc, etc...  If he got his chore list for the day done, he got to stay and do it again the next day. If not, he was out for that day's usual work hours. No access to the house. So, no food, water only out of the garden hose, and whatever weather and temperature discomforts were in play on that day.  When we got home from work, he had to finish the prior day's unfinished tasks, the current days unfinished tasks, all without disturbing us, and ... he could then remain in the home to do the next day's tasks.

We worked that kids ass off. 

This is the burning platform model to motivate a hesitant to launc teen to launch.  He tested  us twice. Both times he was on the curb the next AM.  To facilitate focus, we shut off the internet and cable TV during the work day.

4.5mos later he enlisted in the USAF on the delayed entry program.  He remained our live in beck and call service for another 4.5 most until he got his training slot and we dropped him off at MEPs to report to USAF BMT.

His mom and I are very proud of the man we raised. He is a viable self supporting adult, a man of character, honor and standing in his career and community. All three of us get some laughs out of recounting the ~8mos that he was our live in beck and call chore boy.

The last thing we did for him was buy him a brand new car as a combination Graduation, Enlistment, Christmas gift.  He, the USAF, and the tax payers are covering his college education so we figured that reliable transportation was the last major support we could provide.  He sold that car a but over a year ago.  It ws 11yrs old, had a boat load of miles on it, and it had served him well. He was sad to let it go. It held a notable place in his young adult memories, growing up story, and international adventures at duty stations in Europe. He considered shipping it back to the US after 5yrs in europe but the memories of how bit of a PITA it was to shit to europe motivated him to sell it.  He loves his new vehicle that he researched, selected, and paid for himself.

So, set the expectation, enforce the standards of behavior and performance that you design for him to deliver to your expecations, and light that platform on fire, keep tossing fuel on it, and watch the kid launch.  If he is anything like my SKid... he will thrive.

Good luck.