title: Updating two DataSets with a foreign key relationship
body: <p>I have an application where two datasets are read from the same database. When updating one of them, all the temporary negative primary keys are changed into positive numbers and this change is propegated down to its children.</p>
  
  <p>What works:</p>
  
  <ul>
  <li>Create a row in the first dataset</li>
  <li>Update the first dataset</li>
  <li>Create a row in the second dataset that references a row in the first dataset</li>
  <li>Update the second dataset</li>
  </ul>
  
  <p>What does not work:</p>
  
  <ul>
  <li>Create a row in the second dataset</li>
  <li>Create a row in the second dataset that references a row in the first dataset</li>
  <li>Update both datasets</li>
  </ul>
  
  <p>In the second case, I end up with a negative foreign key in the second dataset. Is there a way to let the positive primary key propegate to another dataset? Or is this information lost?</p>