Entity Framework one-to-zero with different tables

Question

I am wondering if it is possible to make one table related to many.

This is what I got now (working one-to-zero-or-one relation between Report and ReportHeader):

public class Report
{
  public int Id {get; set;}
  public ReportHeader ReportHeader {get; set;}

  [ForeignKey("ReportHeader")]
  public int ReportHeaderId {get; set;}
}

public class ReportHeader
{
  [Key, ForeignKey("Report")]
  public int Id {get; set;}

  public Report Report {get; set;}
}

At this point I want to add table named Style to Report BUT also to table ReportHeader. Thus, the relations would look like this:

Report
|--ReportHeader
|   |-- Style
|
|-- Style

After that the classes should look like:

public class Report
{
  public int Id {get; set;}

  public ReportHeader ReportHeader {get; set;}
  public Style Style {get; set;}

  [ForeignKey("ReportHeader")]
  public int ReportHeaderId {get; set;}

  [ForeignKey("Style")]
  public int StyleId {get; set;}
}

public class ReportHeader
{
  [Key, ForeignKey("Report")]
  public int Id {get; set;}

  [ForeignKey("Style")]
  public int StyleId {get; set;}

  public Report Report {get; set;}
  public Style Style {get; set;}
}

This is so much fun... until it comes to think about the Style class. At this point I have no idea how to design it. Is that even possible to make that class be in two relations with different tables?

public class Style
{
  // ???
  //[Key, ForeignKey("Report"), ForeignKey("ReportHeader")]
  public int Id {get; set;}

  public ReportHeader ReportHeader {get; set;}
  public Report Report {get; set;}
}

Answer 1

At this case you should to mask your desired relation: one-to-one as many-to-one:

public BaseClass
{
    //indeed, collection always will have zero or one items
    public virtual ICollection<Style> styles {get; set;}

    [NotMapped]
    public Style style {
       get { return styles.FirstOrDefault(); } 
       set { styles.Add(value); };
    }
}

public class Report : BaseClass
{
    //other stuff...
}

public class ReportHeader : BaseClass
{
    //other stuff...
}

public class Style
{
    public int Id {get; set;}

    public virtual Report report {get; set;}
    [Index(IsUnique = true)]//to ensure that relation is exactly one-to-one
    public int? reportId {get; set;}

    public virtual ReportHeader reportHeader {get; set;}
    [Index(IsUnique = true)]//to ensure that relation is exactly one-to-one
    public int? reportHeaderId {get; set;}
}