title: Django admin with inlines, 1 model with 2 foreigns keys to 2 different models
body: <p>I have 3 models total. My main model has 2 foreign keys to 2 different models. So the relationships are setup as a many-to-one. When I try to customize the admin, I cannot get it to simply allow me to edit the main character model and have the 2 inlines (universe and series) show up. </p>
  
  <p>What is the simplest way? There seams to be some ambiguity since the 2 foreign fields are throwing everything off. I have scoured the documentation but I must have missed something; I have gotten a more complex many-to-many working in the admin, so this is a bit odd.</p>
  
  <p>Here are my models:</p>
  
  <pre><code>class CharacterSeries(models.Model):
      name = models.CharField(max_length=200)
  
      def __unicode__(self):
          return self.name
  
  
  class CharacterUniverse(models.Model):
      name = models.CharField(max_length=200) 
  
      def __unicode__(self):
          return self.name
  
  
  class Character(models.Model):
      name = models.CharField(max_length=200) 
      rating = models.DecimalField(max_digits=3, decimal_places=1)
      universe = models.ForeignKey(CharacterUniverse)    
      series = models.ForeignKey(CharacterSeries)
  
      def __unicode__(self):
          return self.name
  </code></pre>
  
  <p>Here is my admin:</p>
  
  <pre><code>from django.contrib import admin
  from .models import Character, CharacterUniverse, CharacterSeries
  
  # Register your models here.
  
  
  class SeriesInline(admin.TabularInline):
      model = Character
  
  class UniverseInline(admin.TabularInline):
      model = Character
  
  class Characterdmin(admin.ModelAdmin):
      inlines = [
          UniverseInline,
          SeriesInline,
     ]
  
  admin.site.register(Character, CharacterAdmin)   
  </code></pre>