Honestly, I'm not quite sure what bothers you about this. Sounds like typical teenage behavior. Your DH said no (good for him), and she figured it out. If Nice Lady wants to help out, that's on her. 

You didn't get roped in to rescue, that's good.  You're doing better with disengagement.  Now, time to work on letting it take up your precious brain space, difficult, I know, I still struggle.  Now what color nail polish will you get? ( I read your comment on the other post).  Lol.

I'd rethink this. Start with: she got a ride one way to go where she wanted/needed. She wrongly assumed for the ride home but when told to deal with it, she did. And I'd stop there and focus on how glad you are that you weren't put in an awkward place, what if she'd have called you.  

As far and her and her sister, not your fighting monkeys, not your job. You've been burned, don't touch the stove by allowing yourself to even give it thought. Just assume things will not change and let it go.

My SDs have very bad almost non existent relationship. In her drugging/criminal charges years OSD caused lot of problems for other people and burned some bridges. YSD has hard time letting it go even though OSD is making an effort (making effort for now as who knows if it will last).But they are still sisters.

Some people have complicated or volatile or hot/cold relationships with their siblings or in fact other family members. But they are still family even if dysfunctional. It's quite normal to engage with each other despise troubles they might have. Families are complex. Her sister treating her badly (if that's even true) doesn't mean she can't give her sister a ride. Some people estrange from difficult families but most don't. I'd not expect YSD to fully cut OSD off because of troubles they have 

Everyone deals with dysfunction differently. I have a difficult father but it's mine and my brother's choice to continue engaging with him (in a limited fashion). I'd not expect others to understand our dynamics or assume we must cut him off. 

it's annoying when your SDs complain about each other but I'd ignore it

"When I got home last night, DH was in bed. This man is a tank, so its extremely unusual. His job as a mechanic really rips him up daily. He told me that Sd15 called him asking for a ride back to Toxic Trolls apartment (its her week) from the library near her high school a few towns over, and he told me she had gotten a ride there from her sisters boyfriend...but no ride back. He said he couldnt and to his credit he didnt call me. He knows Im disengaged and knows what that means."

I'm curious as to why he couldn't...too tired or was still working?  

So, because SD22 Feral Forger didnt do the Library pick up, Dad didnt pick up or ask Clove to pick up, and Toxic Troll was working and it was 5:00 pm and raining, she called DH's friend Nice Lady who lives up the street, and who has provided rides in the past. She basically went over Dh's head to ask HIS friend (a really nice lady). 

Teens are resourceful finding rides, teens also manipulate and go over parents head a lot, especially in stepland it's particularly bad.

I understand that she felt a bit desperate. But once again someone is swooping in to rescue her from a bad situation she put herself into. So no repercussions (shes become expert at avoiding repercussions, like her sister) and she will continue putting herself into bad situations that she will need rescuing from. And Nice Lady has to pick up these pieces. To his credit again, he said he gave SD15 a piece of his mind and told Nice Lady that was a no-no.

Rescue from a bad situation? It wasn't a bad situation.  She acted impulsively and normal for a teen.  NOTHING wrong with the library, regardless of reasons, it's a safe and good place to be 'stuck' at.  I don't see why there would be repercussions or punishment for a teen that went to a library and needed a ride home.  Seems completely over the top.  Glad he didn't rope you in though for sure!

Shes of course testing boundaries and limits - like someone here had described these teens are like Veloceraptors testing the electric fence for 1holes. So I get it. Its normal and natural. This is SUPPOSED to happen. In "normal families" this happens and there are repercussinos, kids are told "no", and they argue and thet are told "no and thats the end of things". But in this Upside Downworld of Blended stepfamilies, these Children of Divorce are told "no", they dont like this, so they activate the bio parents against each other. If the stepparent/SO tells the COD "no" they activate the bio parents and entire family against them. And no repercussions.

Yes, this is true.  They activate parents against eachother, they also activate extended family against whichever parent to get their way.  They are rarely punished or told no -especially with guilty fathers or guilty grandparents....so their levels of manipulation are normally a lot stronger in stepkids and it's hard to watch and deal with as an outsider .  It would irk me to no end how many times SD went over DH's head to get her way, it would be activate friends of his, extended family (particularly his parents), my dh's brother, etc.  She learned manipulation very early from BM but his parents actually fed that monster the most.  THEY would go over dh's head all the time, SD learned to put on fake tears, begging, pleading to get her way.  She's STILL that way even now after having her own baby.  

I say this because my ears are always filled with SD15's lamentations against her sister. She took a shoe to her sisters hand. Shes always telling me how badly her sister treates her. So on what planet was it logical to have her sister and boyfriend drop her off at the library a few towns over from where we live (where she goes to high school)??????

Part of the 'pitting against eachother' it's to get pity.  SD didn't have siblings but she would spend 30m-1hr each visit over trash talking her mother to us, and I'm sure she did the same to BM about us.

Also, what isnt adding up, is this kids on winter break - what is the need to go to the library? (hint: something to do with school and grades? I wouldnt know because I dont have access and dont care. second hint: her friends are her life...) 

So - questionsa abound. But its just another page out of the same plotline. Kids allowed to run amok without repercussions.

I didnt discuss any of this with husband because not my circus. And I dont really care.

Don't overthink it, a libarry during break could be grade related, no big deal at all.  I get what you're saying, continue to disengage. She will turn out how she will.

My sd and I get along so much better then in years past, but I've disengaged on how she turned out.  She is still a MASTER manipulator, lier, attention seeker, has made numerous bad decisions from getting pregnant, keeping it, moving out of town, you name it....I ignore most of the crap. I DO vent with DH on oaccasion about it and we bitch about it back and forth. Though we are mostly in agreement lol

I hear ya. Little planning on backstabbers part and its as annoying as hell she isnt reprimanded. Its bigger than the library issue.

Vent away my dear  I GET IT!

Using the new term I learned on here     SD is a BEC!

I just wonder if calling dad's friends was wrong and dad wouldn't pick her up and wouldn't arrange pick up for her, how was she supposed to get home? She needed a ride and she found a safe ride. I am really failing to understand what were other acceptable ways to get home and why those other methods were better. What was punishment suppose to be? Stay in the library? Hitchhike? Was she told to utilize other methods, call someone rather than a nice lady? Sometning is very puzzling here. Like it's all about something else and that something else isn't being spelled out