Are we being unreasonable not to buy my sister's stepdaughter a car and insurance

The onus was on the sister to ask, rather than to assume that OP and her mother would do the same for her stepchild.

Why would her nephews and/or OP be involved in that at all? That’s for her parents and possibly also her stepmother to figure out.

You haven't answered if your Mum is wealthy. Seeing as she could afford private school for two, she is being mean. You and her are two seperate people. I can see why your sister is upset at your Mum. You haven't answered if she calls your Mum, Nan. Your Mum needs to talk to your sister. But that's nothing to do with you. You seem to see you and your Mum as one.

Why would you spent 14k on a child that can vanish overnight?

Normal people, people who raise children in a blended family like they are children in a blended family, will raise kids who don't feel any of the dramatic nonsense you have typed.
None of the frantic, all children are the exact same bullshit. They aren't.
The stepdaughter has her own family on her mother's side. Why on earth are you talking about her father's side? He lives with the op's sister!

If she has been raised in an emotionally stable household,she will not have a problem with this.

It is always entitled adults that cause problems, not the kids.

Step daughter has another parent who should step up for at least half.

This.
the entitlement is outrageous. Perhaps the step daughter’s other extended family on her mother’s side could buy her a car. It’s not for you to fund this. What a cheek.

@SheLovesThat It is very unusual, strange, and weird for mummy and daddy to buy a car for their child. It infantilises young adults and makes them look like babies.

The normal thing that normal teens and young adults do is use their part time jobs to save up for a car.

Surely the stepdaughter has her own grandparents /extended family?

I hate this narrative we must all just accept step relatives and treat them the same as blood relatives - they simply aren't the same and people can't be forced to feel the same for them.

Parents can do what they want, if the child needs a car to get to their job why not get them one if you can afford to? Not a hugely expensive car but a good roadworthy one. If they want better then they can buy their own.

How do you ever save up enough money to buy a car on a minimum wage part time job as a teenager?

These messy situations seem to come up a lot on Mn, and they are so predictable!

I think it would have been best to say something when you made the decision only to do this for the boys.

It’s cheeky of them to expect anything but of course far too late for them to start saving for DSD now

Cant imagine why you wouldn’t treat all your sisters kids the same. She may well be a step child but has been in the family a long time. Youre just creating division. Poor kid 🤦🏻‍♀️

Yeah personally these are the issues to me too.

Theres a huge difference between several thousand and full insurance and £100.

I can understand no one wishing, or maybe being able to afford to totally replicate what the boys were given, but for it to be so different is a bit sad

If the niece is expecting a £12k car and £2k insurance, then yes, she has been made grabby by her dad and step-mum.

I agree with PP that the disparity is a bit stark.
A conversation with your sister would have been good in advance to say that you are not proposing to buy a car / insurance because dsd has a wider family who can be contributing to her car fund. But you would like to contribute and I'd have said a generous sum, a fair bit more than £100. Maybe £500 or something.

Some people on here are so bloody entitled. The girl is a step niece / step grandchild. I wouldn’t want to be obliged to the kid of every person someone in my family shacked up with

Why did you even do it for the boys? That's so odd. If you did it for them, you should do it for the girl. Stepdaughter or not.

The thing is. She actually isn’t part of their family. She has her own

And the OP would still get the silent treatment as its 'not the same'.

There's that, 'we' again. Three/four years ago your Mum had enough money to buy two cars. As said, it's a huge drop to just £100.

I dont think you did anything wrong. I have a "step mum" and "step brothers". They have both parents, me and my brother only have 1. She used to compare us to her sons when my dad bought us things but they had 2 parents. "My son's wouldnt get that", they would just split from both parents so she wouldnt see it, where as she saw everything we got.

As your sisters step daughter has her mums side of the family in her life I think the £100 is a nice gesture.

Being fair to the niece, OP says there's no indication DN does have any expectations. The entitlement is from Dsis. Wonder if she's told her partner DSD is line for a free car too?