To be worried about my step daughter's behaviour?

I feel sorry for her and for you.

Her father obviously doesn't want to spend more time with her, so it will be difficult for you to convince him even if you can get to the bottom of it all.

If she is living with a stepdad and 5 half siblings (?) it's no wonder she is much happier spending time with you, not sure what you can do about it though.

I find it slightly odd that in 3 years and with EOY custody, you have never met SDs Mum. Why?
Would an open conversation with her & your partner about SDs behaviour help?
What is SDs behaviour like at her mother's?

OP ask the open question, don't feed her the reasons. Just ask her why going home is distressing her.

I don't know if she is being manipulative it may just be a simple as she gets more attention and space at yours or on the other end of the spectrum there is something awful happening there. Even if it is just a space/peace issue she is still entitled to want to to live with one parent and at her age her parents should be listening to her.
Maybe there is more to this than what you described but to me your DP sounds like an asshole, unless his daughter has serious form for lying and manipulating I think he is treating her awfully (which probably says something about what it is like at her mums that she wants to stay with a dad who shouts at her and doesn't listen to her).

Ask the NSPCC for advice or give your SD Childline’s number.
Your partner’s a problem - surely he has considered the fact there is abuse?

What a horrible partner and disgraceful father.

She has to tell someone what is wrong. Tell her you'd be happy for her to stay but without a reason you can't make it happen. She can write it down if that's easier.

She will probably enjoy the attention at yours if she's the only child when she's there. Then she has to go back home with younger siblings taking up her mum and stepdads attention. What's her stepdad like? Does he treat her different to his own biological children?

You sound like an incredible step mum.

The fact that she would rather live with her vile father than go home is very concerning.

Can you speak to the school?

If your SD is going to open up, it needs to be with someone who feels emotionally safe. Your dick of a partner is not that person. Screaming at her when she’s upset? Telling you it’s his child and not your business? Not okay.

There is obviously something going on. Maybe it’s a simple as feeling like an outsider due to the other bio DC in her home. Maybe something worse. But you need to try and work out what it is and read your idiot DP the riot act!

Thank goodness she has you.

Does your DSD have her own room at her mum's house. Are the 5 siblings her mum's children or step dads from a previous relationship?

Could she prefer having her own space and more attention at your house. I imagine her mum's house is quite loud and a bit chaotic with 6 children.

OP you sound like a lovely step mum. Ask your step daughter whether you can help her - and whether she can explain what's going on or whether there's anything else you can do to help her. TBH, this stinks of some sort of ongoing abuse. It may be better if a neutral third party (school?) uncovers this not you.

The first thing that comes to my mind is whether she is being abused, either by mum or more likely mum’s partner or someone else that sees your SD a lot. Her dad needs to establish the problem and quickly.

Your partner sounds absolutely awful. You sound like the only person in his daughter’s life who actually cares about her.

So you’re doing the parenting for your partner? He sounds crap, OP, why are you sticking around?

Your partner is a cold, cruel cunt. And an appalling father.

Please do something to get to the bottom of this.

Why thank you for your intelligent insight there. What you have so eloquently articulated ... Actually, no, I don't quite read it that way.

OP, your husband's behaviour is strange. This needs picking apart. I hope the young girl is ok. I'd not feel comfortable with a man doing this,unless theres something more to it.

If you get a moment alone I would ask her what is going on at home which is making her so distressed about going back.

That was my first thought too. I hope I'm wrong.

This is not normal no. This is really concerning and I couldn’t be with a man like that. He clearly doesn’t care how his daughters life is when she’s at her mums. Do not have children with this man, he’s clearly lacking in any fatherly bond / responsibilities

Of course she is, that's why she's posted here, what a ridiculous question!

"Don't make it difficult" !!!!

Good grief!!!

What a mess OP.

And she is just begging. It makes me feel so uneasy. Grabbing his legs, kneeling, saying that he won't even notice she's there.

There is something very wrong here. Teens can be manipulative (I was) but once they realise it's getting them nowhere they usually give up. Her reaction to going back to her mothers is extreme.

I think you need to tell your partner to calm down, his behaviour sounds awful.

You obviously care about his daughter would you feel comfortable trying to get to the bottom of what's going on?

You’ve been 14,OP, you know full well that this isn’t normal behavior.

i agree with @Sunnydiary , could you invite your SD out for a coffee or smoothie and gently ask her why she doesn’t want to go back to her Mum’s?
It may simply be that she dislikes being in a busy house and much prefers the calm of your home.

Your DH isn’t handling this well at all, his child is very distressed and he’s not trying to find out why. This is no excuse, but some people really are crap at handling emotional outbursts.