Save entities with one-to-many relationship using WebAPI

I'm starting a WebApi project and I came across a situation that I did not know how to set my Controller class. I have the following structure

public class Artigo {
    public int ArtigoId { get; set; }
    public int AutorId { get; set; }
    ...
    public IQueryable<ConteudoArtigo> ConteudosArtigo  { get; set; }
}

public class ConteudoArtigo {
    public int ConteudoArtigoId { get; set; }
    public int ArtigoId  { get; set; }
    public int IdiomaId { get; set; }
    public string Titulo { get; set; }
    public string Texto { get; set; }
}

My question is whether I should use two POST calls to API to save each content individually, with the danger of a problem occurring and having the chance of child content not being saved or using a single call to the % with parent% and the same save the contents of the child record?

Following modeling details

• Initially it is good to point out that I simplified the entities to not fill with code.

• When creating an article, you will create it in one language and this article can be translated into multiple languages. A content record will exist for each language.

• The idea of having the article as parent was that the comments and ratings will be of the article, regardless of the language it is