There is nothing you can do to force your SD to relate to you in a better manner, like she used to.  But you can insist on civility, and your DH should back you up on this. Good that he tells his daughter to say hi when she doesn't.  Do NOT drive 20 miles to return something she forgot - she can get it next time she sees you.  Who knows why she started being rude and ignoring you - teen girls can be a complete pain and she may (or may not) improve with time.  Either way there is no point fretting about this, it is what it is. Don't invest any emotional energy in her, or in trying to figure out why.  Be civil but otherwise get on with your own life. 

This is a common story on here. Loving stepdaughters with unstable mothers reject their stepmother when they become teens. It usually has to do with loyalty to BM and believing whatever BS she is feeding your SD about how you stole her father from her and broke up her family.  Also, it often means these girls have learned manipulative, unhealthy relationship skills from their mothers and are following them down a bad path. 
 

Sorry, it's painful, but don't take it personally, it's not your fault. All you can do is disengage. 

She is 20 now and a stripper and sex worker. You did the best you could . Ultimately it's not your child. You aren't responsible for how she turns out

Hi staplepilot, 

I'm experiencing a massive shift in the relationship with my step sons as well, after being in their life for 7 years! It's very distressing. My only coping mechanism has been to completely remove myself from discipline. I am the disciplinarian generally (we have a son together as well) but I am not disciplining the older boys at all. I think they want to challenge us now as they are teenagers and we aren't their moms. (which hurts as I have been!) but honestly we have to keep our peace. 

Let me know if something else works Or a book!

Hi Staplepilot. I too am experiencing this.ive only been in my two DS's lives for 3.5 years, but both girls and I hit it off when we first met. Things with my YAD are still good, and she's a completely different kid than her sister, who turned 16 this week. I would do hair makeup for dun, hair, she talked to me about boys, amd I was the one she came to when she had sex. I didn't approve of her doing that at 15, but made sure to ask if she was okay, if it was consensual, she used protection, etc. I got her to tell her dad, snd we've had the big talk etc. Anyways, at the beginning of this last school year, she stole my car in the middle pf the night, crashed into a parked truck, left the scene snd came home and lied about it. I posted in this forum if you want more details. Then she got in trouble at school for shoeing up super late after lunch with kids who were high (she wasn't), she drinks (BM buys her booze with the mindset she'd rather her get drunk at home than out with frirnds) which neither DH nor I agree with. She's become disrespectful, and typical lazy, selfish and entitled teen. The crash really changed things though since my insurance company wouldn't cover er loss unless I charged her. I didn't want to do that, but she gets messaging from mom that what we're asking for compensation is too high (it's not) and we're always enforcing rules and have higher expectations. She now refuses to come over. BM has been successful at the whole PA thing with her and it's finally worked. I know deep down my DH is upset, and he sees his daughter turning into her BM before his eyes. But he's just done. I think relationships work both ways, and eventually kids need to be responsible for their own actions, including g how they treat thror parents, stepparents, etc. She'll learn the hard way, much like your SD will. Life is short, and I'm disengaging to save my own mental health and wellness and to give my time and attention to my DH and my YSD. I'm sorry you're going through this, and understand how it feels. My friend said to me thst the primary relationship is the one I have with my DH and to focus on keeping thst healthy. When that's the case, everything else will be healthy too. Fingers crossed! 

That puts her in place to actually learn something.  As a minor, she in all liklihood will not retain it on her record.

This sounds very familiar. My DH went for 10 years not being able to say NO to any request from my 3 stepdaughters. Now, he is fed up and trying to say no to them, but they are old enough that it really doesn't sink in. He is realizing that he created one coke-addicted cat-hoarder, one agoraphobic you-tube  know it all, and one bossy, overbearing, OCD brat who eats nothing but plain n'dry hamburgers and wonders why she is constipated 24-7. He is not happy - but he knew what he was doing and he is now paying the price. I, however, have covered my butt so that once these kids all launch (1 out of 3 so far) they will NEVER COME BACK. They will also not have access to any of our financial resources without my permission.

I would just start disengaging (if you haven't already) and make sure everything you buy is in your name only. 

So I have ALL the issues with my SD16. Been there with her since she was 5, she asked/wanted to call me mom and we were good until the last 2yrs and it gets worse and worse.  Mine has a behavioral issue and no one wants to be around her.  She too will only address my DH and then ignore me and my kids.  Luckily after many hard talks with my DH we are on the same page and I am calling her out on her disrespect/behaviors when it involves me or my home.  Otherwise DH has to deal with her.  It is hard! I felt sad to be honest because I still don't know why the dynamic changed..I just accept it and literally mourn the loss of the SD I used to have.