title: Django OneToOne field in admin
body: <p>Here is a model in Django:</p>
  
  <pre><code>class Member(models.Model):
      user     = models.OneToOneField(User)
      moredata = models.CharField('More data', max_length=255)
  </code></pre>
  
  <p>I want to put all the user fields in that model's edit/create page in the Django admin. So I did this:</p>
  
  <pre><code>class UserInline(admin.StackedInline):
      model = User
  
  class MemberAdmin(admin.ModelAdmin):
      inlines = [
          UserInline,
      ]
  
  admin.site.register(Member, MemberAdmin)
  </code></pre>
  
  <p>But Django says that there are no foreign keys to Member on User, which is completely true. Is there a way to fix this?</p>
  
  <p>If I don't use the admin class, all I get is a list of users to pick from.</p>
  
  <p>Ideally, I'd like the <code>User</code> type to be invisible to administrators and have them only create and edit derived User types.</p>
  
  <p>Instead of a OneToOne relation, should I be extending the actual <code>User</code> type instead?</p>