using System;

public class Person
{
    public int Id { get; set; }
    //
    public int RelativeId { get; set; }
    public Relative Relative { get; set; }
    //
    public int OtherId { get; set; }
    public Other Other { get; set; }
}    

public class Other
{
    public int Id { get; set; }
    //
    public Person Person { get; set; }
}

public class Relative
{
    public int Id { get; set; }
	//
    public Person Person { get; set; }
}

//============================================//

public class CemeteryContext : DbContext
{
    public DbSet<Person> People { get; set; }
    public DbSet<Other> Others { get; set; }
    public DbSet<Relative> Relatives { get; set; }
 
    protected override void OnModelCreating(ModelBuilder mb)
    {
        mb.Entity<Other>()
            .HasOne(o => o.Person)
            .WithOne(p => p.Other)
            .HasForeignKey<Person>(p => p.OtherId);
            
        mb.Entity<Relative>()
            .HasOne(p => p.Person)
            .WithOne(r => r.Relative)
            .HasForeignKey<Person>(r => r.RelativeId);
    }
}