title: Multiple Db Contexts with inter twisting relations
body: <p>I have done some searching on DBContexts and was happy to find out i can split them and use the same database. But now i got a problem with my relations i think at-least when i try getting a other entity from a connected entity relation. So here is my code to try and enplane what is happening</p>
  
  <pre><code> public class DataDbContext : DbContext
  {
      // This entity has a relation with a user
      public DbSet&lt;ClanEvent&gt; ClanEvents { get; set; }
   }
  
  
      public class ForumDbContext : DbContext
  {
      // This entity has a relation with a user
      public DbSet&lt;ForumUser&gt; ForumUsers { get; set; }
  }
  
  
      public class UserDbContext : IdentityDbContext&lt;User&gt;
  {
      // Here is where the users are stored
  }
  </code></pre>
  
  <p>Well now i have a entity of ForumUser in that entity there is a relationschip with User, from UserDbContext. I'm getting errors that some keys don't exist. I am thinking this is the problem. This is the error </p>
  
  <blockquote>
    <p>EntityType 'IdentityUserLogin' has no key defined. Define the key for this EntityType.</p>
  </blockquote>
  
  <p>This is so for all the IdentityDbContext tables. I think its is because the Other contexts of cause don't know of that context and its tables is does now know where to get that data from. I'm wondering how other people tackle this problem. With relations between multiple DbContexts?</p>