adult kids dispects me and their mother!

[tg456]

My partner (the mother) and I (no relation to kids) currently live with her 2 adult children - 23, 21 respectively. I've been living with them for 2 years, but in the relationship for 4. The eldest is a little bit more understanding when I comes to her mum's feeling and ambitions etc.
I am only ten years older than the youngest, so this my contribute to the problems??
The main problem is with the youngest, who we both feel may be on the Autistic Specdrome (although she refuses to be tested).

• She refuses to change her opinion and always back answers to any remark made by her mum about herself.
• She constantly interrupts our time, when we're watching TV and we remind her to come back but she pestered until she gets her own way. Interrupt her time though and she tells her mum to 'F* off!'

The main problem is that she walks all over her mum - telling her what to do and bossing her around in a majorly ironic role reversal!
When it's back to the traditional role i.e. mum taking charge, surprise, surprise, she tells her to 'F* off!'
I've tried talking to both of them but nothing works, so much so that about 6 months ago I'd had enough and told her to leave the house. Naturally she hasn't 'you can't tell me what to do! You're even a part of this family!' etc etc.

She demands lifts from her mum all the time, as if she's at school, trips to the supermarket just for her when my partner has just finished a 9 hour shift at work.
In defiance, I refuse to drive her anywhere and we don't even speak anymore. The only positive from this, is that she knows not to voice her opinions to me, as I will tell her something which she won't agree with and then - BOOM! argument!
She also uses emotional black mail towards her mum.
She has been like this since I've known her (17) and hasn't changed.

My main concerns are that my partner gives in to demands so easily to avoid any conflict and when she does stand up for herself, she always feels guilty. I ask her why and she says she doesn't want to let anyone down. She suffers from anxiety and depression and is currently receiving counselling.

Any advice on how to deal with a girl is forever a teenager. confused

Difficult situation there. I wouldn't be so quick to jump to ASD either, if that's her only 'symptom'. I think I'd tell people to f off as well if they came at me with that.
You yourself come across as young, I appreciate that you are upset so perhaps it's just venting here, which is fine and understandable. But my worry is, if you are arguing with this young WOMAN, and you are only ten years senior then you have put yourself on a sibling level with her = no respect and volatile interactions. That will only make your partner's struggles worse.
I understand that it's hard but you genuinely have no right. Only mum has a say unless she has included you as a co-parent and consistently backs you up. And again, she's an adult, so you can't parent her anyway. The best you can hope for is mutual respect. I'd talk to her, see if you can draw a line under the past, admit that you've both made mistakes but that you're there to stay and you want to make life as best and easy as you can for mum, especially as she's unwell at the moment. She needs to see you as a person, not an enemy. Treat her like an adult and she may just start acting like one. No screaming matches, no shows of superiority.
Your partner needs support to get better. If I were her I'd personally be giving these young adults their marching orders, but I'm not and nor are you. I wish you luck and I hope you find a way to fit into the family better.

Surely it's time these two AC left home and managed on their own. They are not children at all - and if their mother is allowing them to treat her this way, there is precious little you can do about it.

You've come onto the scene long after they both grew up - and being only a bit older than them, you're not going to make any difference to this situation. Your partner and these kids are locked into what seems like an unhealthy lifestyle, and you can either like it or lump it. I doubt you'll ever change it.