AIBU to not want to look after DSD anymore...

Poor girl. Issues with her mum and then the man who raised her gives her a home but is away most of the time, leaving her with someone else. Who does she have in her life who wants to parent her properly?

I get that this is falling unfairly on the OPs shoulders and the OP is not to blame, but this girl needs some the adults around her to give her some proper attention and to come up with a better solution.

When does she turn 18 so you can tell her to leave?

YANBU.

DH is taking the piss.

Absolutely fuck that.
You've put up with this ridiculous situation for far too long. She goes home or it's over. They are piss takers!

If you love your DP, don't give him an ultimatum. Have a conversation with him where you explain this cannot continue, you cannot live with the SDD any longer, so she needs to move back in with one of her parents asap.

Poor you and poor kid.

This is one of the more bizarre things I have ever read on here.

This teen is absolutely nothing to do with you. She is a step child once removed! Either her mother or her step father need to deal with her but to expect you, twice removed effectively from being a blood relative, to deal with her, especially in the absence of your DH, is utterly bonkers. You didn't even want children! I know, that if you married a man with children you agree to that life however she is not even his child.

How / why on earth have you put up with this? Your DH and the mother are both beyond CF's, don't enable them any longer.

All of this. The fact that she isn't his biological daughter is a reason for her to feel insecure, not for him to throw her out.

I wouldn't say "Her or me" I'd go straight in with "I'm leaving". That's the only fair way to do it.

Honestly, she just sounds like she could be a normal teenager who is maybe acting up to test the boundaries or maybe has ADHD (re forgetting to lock door and breaking things). It’s hard to tell from your OP whether any of this is her being malicious or just normal teenager stuff. It’s also very normal for teenagers to withdraw from family stuff.

I don’t think an ultimatum would be the best first approach - you should sort out finances - so support from her mum towards her upkeep and address your DH not being there enough. Perhaps some kind of family meeting.

Treat her with respect and kindness, pick your battles - her room is her business - forgetting to close door, work with her to find solutions (sign on the door for example/contraption that auto pulls it shut?).

You need to pack her belongings and take them and her back to her mothers home.
Change the locks. Her bio parents, your DH and your non DSD are taking the piss
They really saw you coming didn't they!!
It has to be a case of she goes or I go, I'm afraid. Either way you need to claim your life back x

Sorry for being a bit thick, but this girl is your DH's DSD with an ex partner, (I'm assuming she was pregnant by another man when they got to father?) and not related to either of you in any way? Why on earth are you putting up with this situation at all? Her mother needs to step up and parent her child. YANBU

Only you know whether you can continue to do this. I would sit him down, not with an ultimatum but with a decision made.

You cannot do this anymore so you are leaving. End of.

If he challenges it then that is the time to put in your requirements to stay. But you have to be prepared to follow through and leave.

To stay I would expect:

• Payments from the mother towards her keep. This can transfer to the child once she becomes an adult in terms of paying board.
• Respect from her with regards to you, your property and communal property.

At 17 I would treat her like a flatmate during the week, but expect DH to pick up the 'family' idea whe he's home. I'd forget the family visits, and the messy room (as long as it stays in her room). She's a teenager- sadly it's a phase many go through.

@spottedinthewild added whose house is it?? it it owned or rented and whose name is on the rent book or lease?

Jesus OP YANBU

This is a private fostering arrangement and social services need to be aware that DSD is not living with biological family.

Claiming child benefit when child doesn't live you with is fraud.

YANBU but her dad as he has been since day 1 is being horrendous to her.

As an aside, I would never expect a 17 year old to engage with family events they are nearly an adult and mandatory socialisation never goes well and destroys them establishing relationships into adulthood.

@spottedinthewild WTF! not your child and not your hubby's child??? why the hell are you looking after her full time when mother gets the financial benefits!! pack up her stuff and put it on the doorstep. change the locks. speak to her through the window and tell her to go home to her mother!!

Spot on! Thank you

Completely agree with this.

DH is not doing any of the heavy lifting here so DSD can move back in her mum.

The husband needs support? That's all he's been fucking getting. He can't call himself a parent in any way, shape, or form. Not only is he not a biological or legal guardian, he works away all week and leaves the op to deal with everything. He parenting contribution is fuck all.

So you're childfree by choice but have still ended up burdened by someone's else's mistakes?

Bloody hell they saw you coming.

AIBU to sit down this weekend and tell DH that either she goes or I do? DH works away 5 days a week, so I bear the brunt of everything, and I can't do it any more.
He's not parenting as he is not there and it doesn't impact him. He needs to start supporting you and read her the riot act. Either shape up or leave.

and have been told we can't claim child support as bio-mum is already doing this, so we are financially struggling to support her too.
That should have changed two years ago. It's too late now as it stops at 18, unless she plans to continue with college then I think it's 19. Write to CB and tell them change of address. Let them handle it.

refusing to keep room tidy, breaking items, leaving front door open when going out, not bringing pots down, not attending family social events, and basically not doing ANYTHING for herself. Think "If I don't bother someone else will do it for me". She is constantly refusing to do social things with us and DH's family, but will go out with her bio-mum to events
Pick your battles. She can see whoever she wants. Give her options to visit but ultimately there's nothing you can do except physically drag her and thats a no. Perhaps invite your side to visit more.

Tidying her bedroom only impacts her. Just close the bedroom door as you walk past. Let her have dirty clothes on the floor and a stinking bed. If clothes aren't in the communal wash basket she doesn't get them done. However do insist on dirty pots and food rubbish being brought down. She's turning into an adult so treat her like one where it doesn't really impact you. If she won't say if she's home for dinner then don't cook for her she can have toast. If she's messy in the house then get a box and dump everything in that for her to sort. Not your problem if her muddy shoes end up on top of her favourite white jumper etc.

Leaving the door open and creating safety problems IS the one you insist no negotiation on. It impacts your safety as well as negates house insurance.

Oh I'm torn on this - because so many people's (bio) teenagers have a phase of behaving like this, and it would be so damaging to be thrown out of the family home for it. Okay so neither of you are her bio parent, but your DH has been in a parent role her whole life, and it sounds like you've been in a step parent role since she was 8.

However - it's not okay for your DH to be away 5 out of 7 days so you have to deal with it all. It's also not okay for bio mum to take no responsibility. I'd say this even if you or your DH were her bio parent.

I think the issue is that all the other adults are leaving you with full responsibility for a difficult teen, which is not fair.

You must be one of the most agreeable people in the world to have ever put up with this. You are not being unreasonable. Ultimatum time, and you need to mean it.

If you want to go then go but don’t give a parent an ultimatum like ‘it’s me or your child’. You’d deserve to lose badly.

Your DH needs your support, and your DSD is being a normal teenager displaying behaviour that can reasonably be expected of a 17 year old whose parents have let her down. Maybe she’s subconsciously testing your DH to see if he really does love her as a daughter. Hopefully he does and she doesn’t get let down by even more adults.