Thank you all for your responses, there's definitely food for thought.
I really want to stress that she isn't a spoilt or nasty girl. This is partially why I name changed, because there are enough details about our lives here that people I know on mumsnet would absolutely recognise us.
She does have what I consider to be a fair amount materially, BUT this is because I didn't have anything growing up, which was part of why I had her at 17. I didn't envision my life being about anything more than struggling, but when she was here in the flesh, I wanted her to have everything that I could ever reach for her.
I didn't want her to grow up being bullied for having less, or feeling lesser than anyone, or grow up to expect that she would struggle to meet her needs.
So I've modelled to her, you work hard, you pay for what you need to, the roof over your head, your council tax, other priority bills, you put some money towards future expenses, then you make sure you enjoy your life...and I happily pass on most of that to my eldest.
This thread really does focus on what DD receives financially because that is the concern she has brought up. One poster says I'm overanalyzing the financial aspect now to see if there's any truth. I absolutely am!
If she were to sight she hasn't seen me enough, I'd be analysing how present I've been, but she didn't say that.
I'm taking on board lots of people saying that she might feel like I've had a second family, and that she might be feeling left out. Ouch, that must hurt her, and I'll definitely discuss that with her because that's absolutely not the intention or thought and I would hate her to feel that way
Maybe we also need to address concerns for her future.
The plan has always been when she's in further education £100 a week transferred directly to her. In the first year of her further education, she can either be taken to and from by me, or she can access public transport, or use a mixture.
By the end of the first year, I would very much like her to be driving. We have planned that she can have her driving lessons and tests paid for by us and there is provision for an £8k car, we will meet insurance costs.
If she's going off to university following the 2nd year of the course she's planning on doing, then I assume there are excellent transport links around and halls are going to be travellable to uni (I never went, I don't know. I'm lucky to earn fairly well without having attended)
Then the plan is that she sells her car, and has a decent lump sum towards her costs at uni, whilst still receiving the £100pw from us. If the COL issues continue into then, we may then also give her the savings we make on not paying her car insurance. Ontop of the loans, I've always assumed that would give her a fairly comfortable (for a student) lifestyle.
The trips I've listed, are all trips out she's jad with myself or DH or as a family with care being taken to ensure most attention is on her- since birth of her sibling, so things will continue on much the same when there are two.
I apologise for being long winded. I'm trying to keep up with all points!
It's clear we have some conversations to have. Not necessarily me telling her to wind her neck in, or punishment, but to really discuss things in depth, with the insight from this thread, I can maybe use some of people's thoughts to put possible concerns out there, and allay them.
She really is a good kid. Thoughtful, sensitive. Nice. I hate that I've pretty much put her worst foot forward here on this post. Anyone who knows her, thinks really highly of her.
Someone said that this may just be the way that she thinks, being good at engineering subjects, I think that could be right, but she's often not quite so blunt.
Thank you everyone.