Need help for a newly diagnosed type 1

I think being diabetic means having all of those little things imposed on us on top of the condition. I decided I wouldn't take my background insulin when I was a teenager, don't ask me why now but it was all about me deciding and not everyone else. I wanted control and still do if a teacher was awkward with me I'd feel aggrieved to - 'walk a mile in my shoes' comes to mind. She's got loads on and you sound like a lovely grandma x

Yeah I would. You've nothing to lose. You sound amazing

I can only recommend what others have been saying that she takes on the full responsibility for her injections. It may sound harsh but as she is doing them at home it is not a giant leap to start doing them for herself at school. I was diagnosed at the age of 9 and I was injecting myself 2 days after and they said they wouldn't let me out of hospital until I learned how to do it. It may be she has a problem that she doesn't want to do it herself at school for some reason so you may have to dig a bit deeper in that area.
The only other thing I can suggest is that as she is just diagnosed she may be experiencing a honeymoon period and as a result this high blood sugar may just be because her pancreas decided to quit that day while it is normally functioning at a normal(ish) level. You mention her levels are generally stable so this could explain this. Unfortunately diabetes is a very unstable condition at the best of times and we all get these weird high or low readings which defy common sense or logic. It is certainly not a "one size fits all" type of condition or treatment.
Anyway hope you are finding some of this advice useful and let us know how you get on .You're doing a great job by the sounds of it.