title: How to add a new field to dataset without CreateDataset?
body: <p>I have a dataset TclientDataSet where the fields are created by code.
  I need the user to append these with additional fields while preserving existing data. </p>
  
  <pre><code>`MYclientDataSet.FieldDefs.Add(s, ftString, 20);
   MYclientDataSet.CreateDataset;
   MYclientDataSet.Open;
   MYclientDataSet.edit;
   MYclientDataSet.FieldByName(s).AsString := 'Test';
   MYclientDataSet.post;`
  </code></pre>
  
  <p>This works but CreateDataset erases all the data. 
  Is there any way of adding the new field to the dataset? </p>
  
  <p>I have tried many other solutions but none seem to work</p>
  
  <p>many thanks </p>