title: What is the right way to append entity from one manager to another in breeze?
body: <p>What is the right way to append entity from one manager to another?
  Straight forward attempts result in overwriting entities or in warning about the same entity key...</p>
  
  <pre><code>var entity = em1.getEntities()[0];
  em1.deattachEntity(entity);
  
  // assume em2 already has entities
  em2.attachEntity(entity);
  </code></pre>
  
  <p>I believe there should be some in-build functionality for <strong>appending</strong> entries to another non empty manager or for generating an unique key for selected manager.</p>
  
  <p>Any suggestions?</p>
  
  <p><strong>UPDATE:</strong><br>
  I did read <a href="http://www.breezejs.com/documentation/exportimport" rel="nofollow">the documentation</a> and tried to do it via exportEntities and exportEntities:   </p>
  
  <pre><code>    var entity = em1.getEntities()[0];
      var export = em1.exportEntities([entity], false);
  //here em2 already has entity with the same key as entity that I want to add
      var import = em2.importEntities(export, { mergeStrategy: breeze.MergeStrategy.Disallowed });
  </code></pre>
  
  <p>This gives me an error: <strong>A MergeStrategy of 'Disallowed' prevents Picture:#Macaw.Whitelabel.WebAPI.Models--1 from being merged</strong></p>
  
  <p>I really don't understand how to append entities....</p>
  
  <p><strong>UPDATE2:</strong>
  I did discover that manually assigning id of the attached entity solves the problem and error disappears. 
  Is there a way to make it not manually but using breeze?</p>