When you say teachers. Do you mean school or dance / sport? If it’s the dance / sport teacher, they may tell her they’re not happy for her to continue in class right now because of her weight loss. And that will be a decision made for you.
In any case, if she wants to continue her sport, she’s going to need to fuel up beforehand to have the energy to do whatever it is. Do you drive her there? I’d make that a prerequisite and say to her eat this (whatever snack she will eat) really quickly and we can get going. Then ensure she has something decent afterwards as well.
I think firstly, I would talk to her and tell her you’ve noticed she’s not currently eating enough at the moment. She’s a strong, sporty girl and it’s important to have enough energy to continue doing the things she loves. And because of this, you’re now going to be asking her to have snacks between her meals and a snack before bed. She will probably really object as she’s not used to this. And then you can explain this is just what all sports people do.
You’ve has a few suggestions on how to make her food more calorific. Even things like making hot chocolate with cream all adds up. She does also need carbohydrates. If she’s eating carbs daily, like the dumplings, stuffing, potato, all well and good. If not, you can explain carbs give you energy. And after a while if she cuts down on food and cut things out, she will eventually not be as strong and won’t have the energy to do all the things she loves. I’m betting right now she’s not feeling that way. It isn’t uncommon to have oodles of energy until you suddenly don’t. And the sudden drop in energy will come if this isn’t turned around.
Whilst 1400 calories won’t see super fast weight reduction, it is about half what she needs to be eating to just maintain weight on that much exercise. So it isn’t safe to be doing this amount of sport. At some stage really soon, she’s going to start breaking down muscle mass for energy. And the heart is a muscle. This process may have already started, as it doesn’t sound as if she had much fat to begin with. As Girlie said, she probably needs to be eating more like 3000 to gain. So if she refuses to eat more, then yes, you need to stop sport. And if that happens, I would then say you’re going to need a rethink about the holiday next week, because it’s going to be too much.
Idk how helpful the GP will be. Hopefully they will. It isn’t at all uncommon for dads to be in denial. And mums as well. I was for a while. And dh far far longer than me, including when dd was really very poorly. As for the ski trip, that’s 2 months out. A lot can change. She can’t go having just what she is right now. But one step at a time.