OP, let me tell you a story.
Some 12 (gulp) years ago our eldest was taking part in a ballet show. Large local theatre. She was 3 in the March and the show was the following July. Not yet at school and was looked after by grandparents rather than attending nursery.
I got the when and how details about the show a couple of weeks before and like you, my anxiety was sky high. We’d got a second child by that point who was 18 months old. I could not understand how I could leave this precious bundle with these people she danced with for only an hour a week! Had it not been for the baby, I would have camped outside the stage door!
I can’t now remember what changed my mind, but I did and she went to the show. I will admit to having written our name on her torso with telephone number in case she went astray from the theatre.
And completely over packing snacks and drinks!!
She LOVED the show, What I learnt is the dance schools have chaperones (council registered I think) and have so much experience in dealing with all the kids in that situation.
I would, in your situation, ask if you can take her out in the interval of the two shows. Just so you can be sure she’s eaten and drank.
12 years on, she still dances at two different dance schools. They have done shows in London as well as loads of local ones. They even went to Disneyland Paris to perform . She has so many dance friends ( I was never a dancer so didn’t understand this bond) and she always looks forward to shows, not just for being on the stage but the whole experience. Crikey, did they miss the shows during lockdowns.
All our other children dance too (their choice, not mine) and despite being really different personalities, have always coped at the shows and enjoyed them immensely.
However in saying all of that, you know your daughter best. There will be plenty of other years to dance in shows.
Just get the tissues ready when you do first see her on the stage.