To miss dd's school presentation or AIBU to change booked plans with friend

Exactly this. She needs to understand that you have made a commitment.
And what is this need to have entire families at everything anyway? It's just not practical.

No way would I change those plans for a year 8 presentation. She will have her dad and sister there.

Don’t even consider it. Agree with all the posters above. All sensible comments. Don’t cancel. It would be unfair and hurtful to your friend. It’s a random unimportant Y8 presentation. She has other family members there. These things happen all the time in life. Parents miss kids performances, open evenings, award ceremonies etc. all the time. It’s just a fact of life. If you make a big deal out of it, she will make a big deal out of it.

Don’t handwring about this to your child either or apologise profusely. As others have said, just say “that’s a shame, tell me about it when I get back!” It is extremely important and healthy for children to see their mothers have passions and hobbies and interests that are valuable and that sometimes these should take priority over a child activity or interest.

Don’t cancel. Her dad and sister will be there.

dont change your plans, its a presentation not graduation and her father will be there. It’s not realistic for your both to be at everything, share the load and let your daughter see that as well

Totally agree with this.

Stick with your plans and don't cancel the trip. Her dad and sister are going and it's not that big a deal in the grand scheme.

Dad and sister will be there. No I wouldn't chnage plans

Her dad and sister are going!
Sorry she’s being a bit spoilt and manipulative. Life isn’t all about her and it’s not like it’s her graduation!

If you are seeing the same concert two nights in a row, I would leave to see my daughter.

Also don’t berate yourself or hand wring over it to her. A cheery “oh shame about the clash but dad and sister will be there and I can’t wait to hear all about it”

Yes definitely keep your plans and don't let your friend down. Your daughter will have her father and sister there. I also wouldn't spend too much time telling her what a shame it is and how sorry you are etc - I would be saying in a breezy way that you will want to hear all about it when you're back but the more you make a big deal about not being there, the more it becomes a big deal to her.

I agree with PP. I don't think it's really healthy for children to know that their parents will re arrange a long planned holiday just because of a date clash with something that isn't a complete one off (like a graduation or wedding). If I was your friend I'd struggle to forgive being ditched on a weekend away for a year 8 school presentation

I wouldn’t, and I’m the parent who (due to schedules as well as personal preference) shows up to every single school thing. She will have her dad and her sibling there, it’s “just” Y8, and you’ve booked a pretty expensive and special event.

What Thea has said is an excellent point too, re her father’s presence

It wouldn't occur to me to change my plans. She's got a parent (and a sister as a bonus there) it's attended. It's understandable that she's disappointed, she's a young teenager, but both parents for a not hugely significant year 8 presentation isn't the norm/necessary. Whilst of course I'd be understanding of her disappointment, this seems like a great learning opportunity that your plans matter too.

I wouldn't.
I think it's really important for women to demonstrate to children that, while they might be the most important thing in your life, that isn't the same as them being the only important thing in your life - that you have relationships and interests and responsibilities outside of being just "mum," and those matter too.

It's also important to demonstrate that once you've made plans with someone you shouldn't then drop them at a later date when you get a better/different offer.

Some kids won't have anyone there at all, either because their parents aren't bothered, or don't have childcare for younger siblings, or work shifts. She'll have two family members, that's more than enough, and she can tell you all about it when you come home.

If I was your friend I'd completely understand if you changed plans if your dd was a finalist in some sort of national competition, but for a random internal school project in Year 8, I'd be a bit annoyed, tbh.

This ^
Im the type who attends everything - I usually attended both evening performances of DD in primary and secondary but it’s only because DH mostly couldn’t so I was the only one available ( plus DD has additional needs so every performance is a really big deal for her) . In your circumstances I’d ask them to do lots of pictures, encourage her to perform just for you before (or after) and send her a lovely good luck message beforehand. I wouldn’t change my trip.

Absolutely this.

Don’t feel bad either op. It’s important that dad is seen as a parent with as much value as you so his presence should suffice.

You sound like a lovely mother. But no I wouldn't come back either. Enjoy yourself.

I wouldn't change my plans for this either

I would come back if it was an end of school thing but not for this as she'll have another parent there. Get Dad to video a bit or take some pics.

Nor me, if the daughter has another family member there.

Stick to your plans. She isn’t going to be left with no one there.

This isn’t just a lunch you’d be missing.