Everything you said is spot on. 

It is so hard because we generally want to be liked and accepted by our husband's family but often they have no idea what it's like to be in our position. It's so easy for them to sit on the sidelines and throw in their two cents and opinions without having to deal with the stepkids affecting THEIR lives 24/7. 

Your MIL didn't want to deal with the opinions of others re.SD's pregnancy at 16 because they would probably sound a lot like my opinion..... "well sorry but it was dumb and irresponsible thing to for SD to do. At that age you can't take care of yourself let alone a baby. Obviously she is going to be relying on other people for help raising her baby and frankly that would annoy the heck out of me. I would refuse to lift a finger. If you're old enough to have fun in bed you're old enough to figure out how to deal with the consequences yourself." 

I don't bring things up but if someone asks me directly, I wouldn't sugar coat it either. You can say your peace in a tactful way and that is what I'd do. Yea I sort of worry about what the relatives think but it's not going to make me chance my ways to suit them. I'm not close at all with LI and I never will be. We have a basic level of respectfulness that I would have towards anyone else but we are not close. Not at all. I keep my distance and that's it. If anyone cares to ask why, I would tell them (in a tactful, emotionless way)

Remember the relatives don't pay your bills. You don't owe them anything except reciprocal civility. You don't have to pretend to fawn all over SD or pretend she walks on water. If MIL made the comment about the pregnancy opinions I probably would have said "While I can understand your reluctance to deal with the negative opinions of others, I do think concern is a reasonable response to this situation given how young she is and the lack of financial stability, maturity, and resources needed to raise a child effectively in these modern times".

Noticed alot of discussion around struggling with any meddling relatives  or anyone's assumptions about what the role of SM is "supposed to be."  
 

most clueless judgmental people assume you're supposed to have a skid on your hip 24/7

I literally will tell these people ... if you're so concerned about the skids you're more than welcome to come pick them up 

you'll usually be met with complete silence because they judge you for something knowing good and d*mn well they wouldnt do themselves

Yep, opiniors are like assholes.  Everyone has one.  However, the opinions of assholes, or idiots, are less than.....

Supposedly, everyone has a right to an opinion.  However, no one has a right to have their opinion listened to much less considered.

I find that when the opinions of assholes or idiots are expressed they do not recognize them as opinions, they act as if their mere opinions are facts. Which invariably they are extremely far from.

MIL not wanting to hear family opinions on SD 16 drop out/ willful teen breeder says all that needs said about how much of an idiot, and probably an asshole, Grandma is far more likely than not both an idiot and an asshole.  So, point those things out to her when she oversteps which she invariably will.

Point out that SD was under the care, feeding, and parenting of MIL and FIL when she ruined her life and the life of a baby.  Then, as this tragedy unfolds and SD delivers idiot move after idiot move in her life, point out to grandma that if she had engaged those with intelligent opinions the outcome for SD would have invariably been far more successful than what MIL facilitated.

Idiot that she is.

Grrrrr.

Take care of you and do not let idiot assholes invoke guilt.  You have nothing to feel guilty about. MIL should be ridden with guilt but lacks the cerebral and character development to recognize it.

Write her off and keep in mind that she can F-off.

Take care of you.

Yes to all of what you've written. I am usually vague with my MIL when she asks about the step kids. "oh I don't know what they're up to I haven't talked to them lately." (excuse myself to go to the bathroom). She prys a lot. I do struggle with how people perceive me. My sister in law doesn't ask questions but I always just feel weird about it all. 

The older I get the less I care about other people's expectations.  So in that way disengaging gets easier.

This topic for me is always interesting. I met skids when they were 12,11 and 8. They are now 21,20 and 17. They lived with SO full time since his separation in 2011. Stopped going to BMs completely in the beginning of 2018. 

I saw a reel on instagram the other day of a woman naming her son after her stepdad. It's the stepdad in the hospital holding the baby while the woman tells him the baby's name. He starts crying etc. He had been in her life since she was 11 and she is currently 26.

Here is the society difference. I've gone above and beyond for my stepkids giving them things I never had... two of them "get it." SS21 and I do not speak.. I can't ask him simple things without getting attitude. I genuinely just don't like him. 

Men are getting baby's named after them woman mainly get sh*t on from skids. We will always be viewed different as the 2nd or 3rd wife... even WHEN the BMs are completely lunatics. 

Society has always pinned women against each other.. no denying that.. In todays society where 1 in 2 marriages end in divorce kids have become more like pawns in mentally unstable game of who's better and we have forgetten the bigger picture of life. 

Ughh MIL and FIL love the old sweep under the rug method. They ask how everything is going and it's just fake conversation on my side. They don't want to know about Toxic BM and they are in complete denial about their two grandchildren and their behaviour. As soon as the truth starts to seep out in conversation they busy themselves with something else, excuse themselves from the room or brush it off. FIL actually states to us he doesn't want to hear it.

So, we don't tell them anything, pretend we are a happy Brady bunch family and treat family gatherings as bandaids - rip it off and it's done until the next one. 
 

I remember one time SIL asked out of conversation where SS was going to high school next year. BM at the time enrolled him into a private school behind DH back and signed his part of the form with her signature. So it was a stressful time for us as DH was seeking legal advice, and threatened BM to court. So when I told her 'we have no idea, apparently a private school as she enrolled him behind our backs and won't agree to any public school he is zoned for' she immediately looked uncomfortable and then made some excuse to walk off. That's the support DH receives from him family.  Sorry SIL what was I supposed to say? Oh that's right the vague sweep under the rug answer of 'oh not sure yet' and smile and wave. 

An interesting example of SM being recognized, loved, and honored.  In the mid 70s we came back to the States for 4yrs before heading back oversea. My parents bought a home in the suburbs of a major city.  Across the street was a single divorced dad and a boy the same age as my younger brother.  Mom and dad formed a close friendship with the man.  His son and my brother were inseparable.  

The divorce backstory there is that the man and his XW adopted the boy and a girl who was a few years younger. He got the son, XW got the daughter.  Typical visitation schedule, back and forth where one kid would go visit the other parent then both kids would come back to spend time with the parent whose kid had traveled to the other parent.

The dad met and married a slightly older woman who he met a work.  They raised the son together and partnered in countering the XW's bullshit.  She whacked out, joined a cult, took the DD into the cult and when the DS would visit her he was integrated into the cult as well. The kids were all housed in gender segregated  supervised "dorms" that were basically body warehouses/barracks style sleep areas.  On the last visitation the DS had enough, took his little sister and walked away from the cult compound hiking for miles. He called his dad when he got to a phone. Dad had just landed in their city after dropping the son off for mom visitation and immediately jumped on a plane back to mom's city.  His XFIL picked him up at the airport, they went to get the kids from the police station, he took them back to his home, and mom never again had custody.  She only had extremely rare supervised visitation overseen by her own father who was team dad all the way.

Both kids worship their SM. She is their mom.  "Mom " is rarely if ever mentioned and the stories of the rare events she showed up for are truly bizzare.

Both kids are successful, well adjusted, and extremely close to their dad and SM.  The esteem they hold their SM in is absolute.

Certainly being a StepDad i frequently s far easier and frequently far more successful than being an SM.  For some reason the SKid revulsion to an SM seems mandatorily visceral where as a StepDad rarely has to go through that at least not to the same level of vitriol that seems to be the case for SMs.

I do still worry. I'm lucky enough that the SKids and in laws live almost 5 hrs away so I don't see them often. But the problem is that most of my husband's family doesn't know exactly how little he sees his kids and so when we go over there it's super awkward. His kids don't like me and I don't like them. We recently went to Alaska to see his sister who he hadn't seen in a few yrs. His mom was there to. She kept telling me, my husband and his kids to get together for a family picture and I kept backing away and managed to get out of it each time because I do not want to even be in a picture with them. The sister did ask me when we were alone what it's like with them at home (she could see how terrible they are). I told her they really don't come over but a handful of times during the yr and it's a quick weekend, or husband gets an airbnb and goes there for weekend. I think that was eye opening for them to really hear for the first time the reality but also she got to see how bad his kids are first hand. 

I hate going over there but if I don't go with him half the time his stepmom and dad and sister start asking why I don't go and who knows what else. Then when I do go they constantly say things like oh the kids are just so sweet it's so good they have you guys or here come sit next to SD and i just make some excuse to go to another room. I just smile awkwardly and say sure.  They totally have it in their head that we're close or something when it's clearly not the case. My husband is either oblivious to it or he doesn't tell them the reality so that he doesn't shatter what they think the situation is. But then I'm conflicted because on the one hand I think, don't push me on them when it doesn't take a genius to see that there's 0 relationship there. Then again, maybe they see that and that's why they seem to push them on me so much? I also think well shoot they probably think I'm horrible or who knows what they say when we leave? Or, it's not the kids' fault they suck so maybe I should try harder? Then when they're in my house I get up and say good morning and the brats don't even look at me, don't say anything and my husband acts like he doesn't see it. I've been letting it go but I think it's getting to be time I say something. 

His parents will say things also like it must be so hard that you probably don't get them enough and my husband will bs some answer and I just sit there with a stupid fake smile not saying anything but secretly thinking ya, I don't think I can handle teens leaving shit in the toilet more than a handful of times a yr or now im worried about the SD during her time of the month because she left blood in the middle of the hallway, not sure how exactly but ya. I made him clean it and I told him to talk to her and him about proper toilet use and idk if he has. I think his family may have some opinions if they knew those things and everything else but I'm not gonna tell em and then I think, who cares? I go back and forth between caring and being full of anxiety about it to not caring. Maybe there is no solution, I just try to stay away as much as possible so that I don't have to deal with those feelings.