With a list being here now:
https://en.wikipedia.org/wiki/Brazil_at_the_2024_Winter_Youth_Olympics
Although that list is not entirely correct. It is in terms of athletes (as far as I know), but not exactly the sports. Julia Reis will indeed do cross-country skiing, but Mariana Silva will be doing biathlon. Nobody really understands why, because in the only IBU Junior Cup in which both competed, Julia was 14 minutes (!) ahead of her, but alright, the ever so mysterious ways of Brazil's snow sports federation I guess
I'll ask if the boys are correct, or if one of them is also going to do biathlon.
Edit: Mariana will apparently do both cross-country and biathlon, while Julia will only do cross-country.