I read your other post and didn't comment there because others already had.
To answer your questions as plainly as possible I will firstly say yes, of course disengagement is possible and has been achieved by many people on here, including myself.
You don't sign up to it-it is a process by which you protect your own dignity and self esteem, but every disengagement is unique to its own situation.
You disengage from your SS (who sounds like a very messed up and toxic individual) in any way you see fit to protect yourself. In your other post you said you were frightened of him and you were worried that DH might be considering letting him move back in. You have a right to peace in your own home- when we bring children into the world we expect them to grow into functioning adults who will become independent and responsible people. Sometimes it goes wrong, but allowing a messed up adult into your home when you so clearly don't want to is not the answer.
You cannot shut off that part of your DH's life- he will always be a parent and by the sounds of it you will never be-you admitted what a terrible parent DH was.All you can do is leave them to sort out the sorry situation themselves.The shit you find yourself in you didn't make-therefore you cannot fix it. Insist SS doesn't let him back in- that much you can control, but if he does then you really have to re-assess whether you want to stay.
Do spouses have to be in agreement? Ideally yes, because the offending spouse should be putting the needs of his other half first. However, in practice it is often the case the the offending spouse will not accept the disengagement- it makes the situation more difficult but once the skids are out of your life you will re-gain the self-respect and confidence you had lost and sometimes the situation gets better and the couple become close again.I am still hoping that this will happen with my DH.
It isn't possible to tell someone else how to disengage, you have to try to do what is best for you. My advice though, is to be firm with DH about letting SS come back to even stay in your home because if you back down on that one it will be very hard to get back to where you want to be, which is free of this toxic adult who was messed up long before you came on the scene and is not in any sense your responsibility. Put yourself first...

Hi again LadyT

You will find more people on here during the week. Many of us have limited time over weekends but we DO check in and also to help anyone in crisis.

Its not the best idea to have anyone move into your home that should be standing on their own two feet. Emergencies are different. We all know what an emergency is, right?

But of course, leave dates and contracts may be necessary.

DH can help his adult son as much as he wants too but since your married it should not interfere with your house hold budget, retirement fund or bills. THAT is common sense. Perhaps gift ss 1st and last months rent, 1st electric bill. IF he feels so compelled to.

Has ss committed crimes that he was punished for? He is a drug user, drunk, no job ? HuGE NO NO's....for allowing to squat at the parents house.

Watch Dr. Phil for a few times IF you are doubting that you may be unfair about that. SS should be out and on his own.

I disengaged in 2003 or 4, years before I had come across StepTalk, and I didn't even know there was a name for what I was doing. I just knew I had to take a step back for my own self preservation. I stopped going out on outings with DH and my two SDs, who were then young children, because one of them constantly sabotaged the outings and DH didn't have the nous or the backbone to stop her doing it. I was civil to the SDs when they came EOW, (although didn't try to engage them in conversation) and continued to cook them a main meal, except for a few years when they refused to eat my food so I made DH do the cooking.

Similarly, in the decade to follow, he allowed himself to be bullied by NPD BM, and allowed his daughters to disrespect me, choosing them over me in arguments about behaviour and defending their bad behaviour constantly. He was afraid of losing contact with them, which is his explanation for not defending me.
Eventually he stood up to NPD BM, though it took about 5 years for him to learn to do this. It took longer with his daughters, and he will still say things to this day, like "they're young, they'll learn" and they are now 21 and nearly 23. He does see their faults a lot clearer now, though, and realises that he didn't always behave well in those years, and has apologised to me for this on more than one occasion.

Here's the link for the disengaging article, in case you haven't already seen it: https://www.steptogether.org/disengaging.html

I didn't tell my DH I was disengaging.

My SS is a recovering addict, and while his parents enabled that behavior, it was nothing like what you're experiencing. Still, there are some similarities. I just stopped doing things for SS (I had other plans, had to work, whatever), and stopped "loaning" money to DH. That was really the most difficult part for us, but I was enabling the enabler and the whole situation was just toxic and unhealthy for all of us.

I support DH's relationship with his kids. He can visit them whenever he wants to. Both SS and SD are invited to our home whenever they want to visit us (they live several states away, so it's not frequent, and both are respectful house guests). But DH is responsible for cooking, cleaning, meal prep, entertainment. If I want to join them, I will. If I don't, I don't. He is responsible for remembering birthdays, their Christmas gifts, etc. I might participate and I might not. I don't think DH has ever caught on that I am "disengaged." He does know that both kids have at one time or another driven me crazy. But since I stepped back, my relationship with both have improved immensely.

When DH talks about his kids, I generally say something along the lines of "that's great" and if he's nonstop about them, I'll change the subject or find something else I need to do. I'm not rude. I'm just not engaged. Sometimes his kids still take up way too much space in my head though, and I'm working on that. It bugs the beegezus out of me when SD and DH talk multiple times and day and text throughout the day. But unless it affects me, I don't say anything because that's being disengaged too. If it DOES affect me, it's because DH takes a call or interrupts a conversation to respond to a text, and my issue is then with DH for being rude, not SD.

There is some finesse to be learned and skills to practice. But you can have a very happy marriage and support your spouse, even though you don't have a relationship with his kid.

LadyT - your skids are adults, there's no need to talk to your husband about disengagement. Simply do it

In short, you treat skids as strangers, greet politely and that's that, you do not engage with them in any way or form... they are adults not children. Yes your husband will not like it, but he can simply suck it up.

You do nothing for the adult skids, you do not even buy them gifts...

Think of them as bratty strangers you pass in life...

Find things for you to do that makes you happy, if your husband wants to spend the Saturday with his baby to watch football, so be it, you go out and enjoy the day with friends, family, walking trails, reading books, you will not be running around the house cleaning and entertaining them, DH's guest he can do all of that, heck you do not even buy snacks, when you come home, you are all over DH for cleaning up after his party, you do not touch anything....

You are an adult, it's your choice who you want to social with and whom not,

I think you are misinterpreting what disengagement is. You are not shutting off that part of your SO's life, you are shutting off your participation in it.

Basically... the adult toxic prior relationship spawn is not allowed in proximity to you. IF you are at home... the SKid isn't there. If he shows up either DH grabs his coat and the two of them leave .... or you grab your stuff and head out for a mani-pedi until the Spawn is gone.

If the toxic spawn behaves inappropriately in your presence you confront it immediately. If DH doesn't like how you interface with his toxic spawn then he can step up and get it done before you have to.

That is my interpretation of disengagement.

Lather, rinse, repeat.

DH & I "agreed to disagree". After 4 years of battle over my disengagement from SD57 and SGD 34 (mother/daughter). This is where we are today.

My wife and I have really only ever fought about her youngest son. Some of those fights almost ended our marriage. Her son has severe anger issues to the point that he gets violent. He is horribly abusive when he doesn't get his way. He is a child in a man's body. He dropped out of high school, and hasn't really ever worked for anything. He's perpetually high. He is bipolar (at least) but refuses to do anything to help with his mental health. His life is a continual roller coaster that I was also being strapped onto. I eventually had no choice but to disengage. The last straw for me was her son telling me that he is my wife's kid, and I am just the piece of shit she married. He told me he knows she can, and has seen her, do better than me. He also brought my dead mother into it. That was when I decided I had enough, and it was time to disengage from him completely. I had to put my marriage on the line to do it. I had a frank discussion with my wife. I told her that I can not make the decision for her to stop putting up with her son's abuse. However, I am making the decision that I and my kids will no longer be put in that situation. I don't want her son in the house. Period. He's put his fists and feet through walls before when he was asked to mow the front lawn. I told her that if I had to remove myself from our relationship to keep myself and my kids safe, then that is what I will have to do. Her insistence that her son be in the house was giving me no other option than to consider the end of our marriage in order to keep myself and my kids out of an unsafe situation. I told her that I was getting off the merry go round. I support her relationship with her son, but it has to happen somewhere else. When he gets out of control, it becomes a scary situation very quickly. I told her that if my parting ways with her son is a dealbreaker for her, then I want to know that sooner than later. I was ready to call it quits. She finally saw the light, and things between she and I have been steadily improving.