Family basically falling apart

This has not happened over night
this is the upshot of years of passive parenting

I disagree. It's not normal to bully, steal and swear at your mother. It may be recognisable behaviour, in that some teens do behave in this way, but it is not normal.

I have had teens and work with teens - I recognise the kids like op's 14 year old. They are troubled kids who cause trouble (sorry op)

Change WiFi password and make DD2 earn the right to it.

change it nightly. She can have access everyday she sits a dinner table and politely engages with everyone.

same with pocket money. Split the monthly amount into a daily amount and she earns it through respect. At the end of the month she gets what she’s earned.

To change behaviour is an effort. If she’s going to make the effort she gets rewarded. If she doesn’t ….. well tough!

i grew up 3 years older than my younger sister who is like your 14yo. I was quieter like your 17yo. It’s a horrid environment and I left the country at 19yo because I felt the same as your DD1 - I wanted to get away asap.

It sounds like fairly normal teenage behaviour. It is likely that in 10 years time they will have matured and get on fine. It's just teenagers being teenagers. Go shopping with only one of them at a time to avoid the hassle you describe.

I hate to be brutal but you need to start behaving like a parent, and stand up to your 14 year old, she sounds like a tyrant. You’re the adult in this scenario, and it’s about time her actions had consequences. Don’t make empty threats, and follow through on any punishments you hand out, you clearly haven’t been doing that and as a result she believes she rules the roost, because she does, and you’ve let her. If she swears at you then you confiscate her phone.

Parenting teenagers is hard work, but you’re making it harder for yourself and your other daughter by allowing her to do as she pleases.

My approach would be a bit different from most

Praise the behavior you want to see eg when 14 year old is nice and kind, comment on it, rather than focusing on negatives all the time

Positive comments should be personal. negative comments shpuld relate to behaviour eg "you were so kind today" is more powerful than "that was kind". And, "that was unkind" is better than "you're unkind"

Removing WiFi and pocket money are arbitrary punishments. Better to focus on natural consequences eg you were rude this morning and your sister was upset, so I think it's best you don't come out shopping with us this afternoon. Or, last holiday wasn't pleasant for me because of your shouting so I think we won't go away this autumn

Some cheek and pushing boundaries is age appropriate but if other parents are telling you your child is out of line, I'd thiink that's a concern

You can't because your 14 year old ruins it by being horrible. Go out with your older daughter and hide any valuables that she could possibly steal.

Even if their dad is overseas, surely he can speak to his younger daughter about her awful behaviour. He can't just opt out of doing any parenting.

It sounds more like you don't leave them at home for a few hours or an evening, if this is true, why not?

I feel you have come on here looking for a magic solution when in reality you need to do some very tough and consistent parenting to the 14 year old. And no, sounds like you need not be going on holiday this year.

it must be tough parenting alone so you need to have a very honest conversation with your ex to say you are struggling and he needs to offer some support somehow, someway.

Counselling and get the dad involved, even if he leaves away.
14 year old girls can be horrible with their mum!
Looks like sibling rivalry

Change the WiFi password. Don’t back down. Your 14 year old has derailed and needs a lot of guidance. Give yourself a year to help her become a nicer person

If the relationship with their dad is good he needs to step up and help. Take unpaid leave and come to you for a time to help work out what is going on and to enforce boundaries. You are doing your best but of course you can't do it all. No judgement from me. This has the potential to be very damaging for both girls and a dramatic intervention is needed.

This is not teaching her anything, it's just giving mild criticism to make her feel bad. She will get worse if you keep that up. You need her to imagine how it feels, to consider the impact on her sister, to consider how she wants to be perceived in life, to think of other ways to behave and how that will improve her life and her sister's life. She is acting up to try to get you to parent her and you need to make at least some effort to do so.

How is she thriving at school if other parents tell you she’s a bully? Maybe she’d be less nasty if she struggled a bit.

Your 14yos behaviour is atypical.

My kids dont get on. I rarely take both out together now. It helps hugely.

I do wish there were hormone meds for adolescents...

In some ways it is good you see DD2’s behaviour with her sister because 100% she will be the same at school, if not worse. She is showing you what she acts like with those she perceives as weaker or different to her. This is what I’d focus on.

I’d speak to the school to see if she acts the same at school and would set up counselling for her to explore her feelings. For sure any rudeness to her sister should be punished but you sound afraid of her.

Is she doing Duke of Edinburgh? A kid like this volunteering in a charity shop or visiting the elderly just might help her see how the world is not as straightforward as she thinks it is.

This is not dissimilar to the relationship between my sister and I. I was the geeky older sis, and my younger sis was a complete nightmare, towards me, my mum and the rest of the family. Everything I did was a huge embarrassment to her, and she displayed a lot of worrying behaviour (even got arrested on one occasion).

Just to shed a little light. My sis grew up, and I moved out, and we became the absolute best of friends again. My sis can still be difficult from time to time, but she is a law abiding citizen with a job and a beautiful daughter (who is a much more pleasant teenager) 😂

Your 14yo needs discipline. Start with the wifi, as you do, pocket money, but if she still doesn’t behave properly you have to find other things she cares about (her phone, you taking her to hobbies or to see friends, hair straighteners, watching tv, etc) and don’t give things back until she stops being so rude.

Instead I think you should try to delve deeper into why she’s doing it. That’s the main issue here.

I was just thinking the same.

Many siblings, once they get to teen years, don't get along. Why? Individual personality issues, petty jealousies, different characters.....take your pick.

I won't offer you advice except one .....get your 14 y.o. to see a clinical psychologist. I don't believe "parenting" as in taking a hard approach to a young teen with behaviour issues, work at all. It'll create more resentment and the feeling she's on her own, even if that's her interpretation of how she feels. Sometimes getting a professional involved can do wonders. They open up with them in a way they won't do with you or any other friend or family member.

It's worth exploring.

Then you can only go on limited holidays.

I honestly don’t think that your biggest problem here is how many holidays you, the mother, can go on.

So, when you ask her why she’s doing it she tells you she’s sorry. Then what do you say?

If I were you I would be asking your husband to locate back to the family home so that you have some back up. Not that I think you can’t do it on your own but obviously it is hard and why on earth is it all on you to fix.