I assume u mean dialogs by forms .
You can always have functions to retrieve the data from dialog.
For eg -

Qt Code:
  1. MyDialog dlg;
  2. if(dlg.exec() == Qt::Accepted)
  3. {
  4. QString text = dlg.getLineEditText(); // You get the text of the line edit here
  5.  
  6. // Now pass it on to another dialog or use it as u want
  7. dlg2.setLineEditText(text);
  8. }
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Hope you get the idea