I think the concerns are more with the husband-wife relationship than the skid-SP relationship. A lot of bio-parents really struggle with why anyone wouldn't completely adore their spawn, and that it's their spouse makes it worse.

If you're disengaging, there really isn't a relationship between you and the skid.

Downsides?...YES!...Absolutely.

..My Blood Pressure is Down
..My Anxiety and Depression are both WAY Down
..My symptoms of Complex Trauma (created by their constant abuse),...also down
..My constant strife with spouse regarding steps..down
..My nervous symptoms...down
..My reaction mode to mental. emotional, and psychological abuse...down
..My Low self esteem levels...down
..My condition created by consistent rejection...down
..My levels of resentment and personal unforgiveness and bitterness...down....

Yes, I must say there are MANY, MANY down sides to disengagement...Enjoy them all!...Peace

Disengagement can be what you want it to be. If you have a good relationship now it can still be good. Do what you want for the child. Only take on what you want to do. Anything else is on the parents. You can be the fun aunt' type person in skids life. Or what ever you want.
Sorry not familiar with the ages or backstory here.

Down side of disengagement.

Well it almost costed me my relationship. I had to make the decision and SO did not like it very much, thus we broke up for a full week after 14 years. SO came back and I simply told him, now never expect me again to be involved with your brat, she's got a mother and she made it very very clear that her mother and step father is the best parents she ever had. Dissing you, if we are going to be together again you will grow a spine and start teaching your 17 year old brat some manners.

There's a fine line between disengaging from the skids and not from your partner. When you are disengaged you say nothing, you simply observe but you sort of start to resent your partner cause he/she can not see how disrespectful the brat is, how they are treated and well you sort of turn cold because your partner has no back bone to teach his/her spawn some normal life skills.

I haven't been able to completely disengage with my SD because it would make life so much more stressful for my DH having to be a single parent and his boss is a jerk about letting him leave work to take SD to appointments.

I'm not sure SD cares one way or the other. I can be the nicest person in the world to her and she'll still stay I hate her and she hates me.

Dh and I have a 4 year old daughter and she's starting to understand that SD is her half sister and I'm not SDs mom and I don't treat them the same. Its a little awkward since my daughter is learning that mommies and daddies don't always live together and SD doesn't see her mom any more. I worry that SD is always going to be jealous and hateful towards her half-sister and the less I do for her, the more ammo SD has against me. I worry the less I do for Sd it just promotes more jealousy of my DD.

I believe the downside is accepting you cannot fix it, but the upside is accepting you cannot fix it... Most of us never wanted this dynamic, but realizing you can never fix it is empowering and a huge stress relief...

The downside is watching other adults parent your husband, and his spineless inability to say or do one single thing, when he knows how horribly wrong they are...huge turn off...everything you have dries up instantly :-).

It is not an ideal situation by any means, but it is the best alternative to YOUR emotional well-being. Bullies who are continuously reinforced are not going to change.

I’m doing a soft semi-disengagement approach. Before I get to what that means for me, I’ll provide a bit of background. I took on SD12 and SS11 when they were both in nappies (50/50 custody with BM). Because I was naïve I through myself in head first thinking I would love the kids because I love their Dad. Long story short, the next few years where hell on earth as I realised what I’d really taken on and I grieved for the life I could have had if I’d chosen a man without kids.

I’ve always had the full backing of my DH, he’s never made me feel like a second priority, never undermines my parenting and never makes any decisions about the skids without talking to me – we are a united team and I love him dearly. For this reason, I stuck it out and it did eventually get easier. Both skids view me as their third parent and have always been very accepting.

However, SD12 has always had a range of undiagnosed stuff going on (most likely ADD, OCD and anxiety) that’s got progressively worse as she’s got older. She’s also lazy, lies constantly, has no empathy, is selfish and emotionally stunted. In short, she’s a very unlikable kid and I can't stand being around her.

Despite my feelings, SD12 is very much attached to me although has been picking up more and more on my feelings for her and complaining I prefer SS11 (which is true).
The more time I spend with her the more irritated I get and the less patience I have to deal with her shit so the soft disengagement is the way to go for me.

For me, the soft approach is about three things: Mindset; honesty and small tactical actions.

The mindset is about not caring so much. I used to feel very invested in the skids lives and worry so much about where SD would end up but now I don’t care as much. If SD doesn’t do her homework or does it poorly I don’t care. When BM finally agreed to get SD professional help this year I think that’s great but I had no involvement in what or how that happens. I hope SD can turn it around but I'm also under no illusions that the most likely outcome is that she will turn out just like BM which means I'll always dislike her.

From a honesty perspective this is about introducing small bits into conversations with my SD who until recently was under the delusion that I was no different to her bio parents. I’ve explained to her that my love is not unconditional and if she continues to display behaviours that so fundamentally clash with what’s important to me (ie my values) then her and I will continue to have friction.

From a tactical perspective, it’s small things. DH now drops her off at school instead of me and they spend more time together on weekends so I can have some space. I now also refuse to have the skids if DH is not going to be around ie travelling for work etc which is something I always used to do.

I’m also more vocal, ie when before I used to suffer in silence I just tell DH when I’m struggling and he gets her out of the house and my hair.

DH is also in a better place these days. He really struggled with the friction between SD and me for a long time, which I completely understand as it must be so upsetting when your partner can’t stand your biological kid, but he has never viewed SD with rose coloured glasses so he understands how difficult she is and has recently gone quite zen about it all – ie whatever will be will be.

I wouldn’t rule out full disengagement one day for SD if her behaviours get worse but I’m personally hoping she chooses to live with BM for most of the time in the near future ha ha.

Main down side to disengaging for me was - I was very lonely EOW when the SDs would come over and DH did stuff with them. I stayed home on my own most times.

I felt I could not comment to them about their behaviour in my house even when I hated it. I had chosen to disengage so I did not feel I could re-engage just when it suited me.

All in all - if I had my time with them over again - I probably would NOT have disengaged. Even though it would have been tough.

I started to slowly disengage from my SO's daughter (13) a little over a year ago, and am completely disengaged now. BM is high conflict (likely borderline) and is a huge reason behind the disengagement. She is horrible. I'd like a relationship with his daughter, but she is a mini version of her mother, and her mother is doing everything she can to alienate my SO. I told him i don't want to put his daughter in the position of feeling like if she likes me or has fun with me (both of which she does/did) that she will be betraying her mom (which is I'm sure how her mother makes her feel). I can guarantee that her mother is saying all kinds of nasty things about me to her, but daughter will eventually see everything for what it is (unless she turns out just like her mom, which is pretty inevitable). But for now, my relationship with SO is great... I've even asked him to stop sharing/showing me texts from BM. I just get too upset and angry with him for not handling her the way I would. He's come a long way with setting and maintaining boundaries and not engaging in her craziness. She's all talk, no action. When she starts with her threats, he either doesn't respond, or says "ok, if that's what you need to do".

I stopped forcing myself a long time ago and disengaged but I will help out in situations like helping get her to school or dr. Anything to help her along the way of a better life for herself. I won’t deny any human being that. Accepting I can’t help what others control was a big stress relief off my shoulders. It does bother me how she comes over and says how hard her Mother’s life is and a bad struggle. All I say is I don’t understand why people live beyond their means. For real I do not want to hear the pitty train about her mom.  I offer she can stay longer for the summer but I know she won’t so it all works out. I think sd stays away because she disengaged from me and I’m fine with that.   

The downside to mine was that he chose them over me and I am now trying to remake my life as an almost 61 year old woman who has to work to support herself and live in sub-standard housing. Is it better than being a stepmom? Yes, you bet it is!