如何将对象附加到JSON变量中

这里的问题是，每次运行循环时都会重新创建类"obj"的实例，因此在循环结束时，我只有一组对象。它应该有几个。

foreach (var project in projectsDictionary)
{
    foreach (var season in seasonsDictionary)
    {
        foreach (var episode in episodesDictionary)
        {
            obj = new Parent
            {
                Title = project.Value, Link = "1", Children = new List<Parent>
                {
                    new Parent
                    {
                        Title = season.Value, Link = "1", Children = new List<Parent>
                        {
                            new Parent
                            {
                                Title = episode.Value, Link = "1", Children = null
                            }
                        }
                    }
                }
            };
        }
    }
}
var responseBody = JsonConvert.SerializeObject(obj);
return responseBody;
public class Parent
{
    public string Title
    {
        get;
        set;
    }
    public string Link
    {
        get;
        set;
    }
    public List<Parent> Children
    {
        get;
        set;
    }
}