How to pass object created in FXML Controller1 to Controller2 of inner FXML control

In FX 2.2 new API for controller-node was introduced:

// create class which is both controller and node
public class InnerFxmlControl extends HBox implements Initializable {
  @FXML public ComboBox cb;

  public InnerFxmlControl () {
     FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("fxml_example2.fxml"));
     fxmlLoader.setRoot(this);
     fxmlLoader.setController(this);
     try {
         fxmlLoader.load();            
     } catch (IOException exception) {
         throw new RuntimeException(exception);
     }
  }

with next fxml (note tag fx:root):

<fx:root type="javafx.scene.layout.HBox" xmlns:fx="http://javafx.com/fxml">
  <children>
    <ComboBox fx:id="cb" />
  </children>
</fx:root>

By this you’ve created a new control, which you can use as regular JavaFX controls. E.g. in your case:

@FXML protected void handleSubmitButtonAction(ActionEvent event) {
    // you just create new control, all fxml tricks are encapsulated
    InnerFxmlControl root = new InnerFxmlControl();
    // and you can access all its' methods and fields including matched by @FXML tag:
    root.cb.getItems().add("new item");

    Scene cc = buttonStatusText.getScene();
    cc.setRoot(root);
  }

and in fxml:

<InnerFxmlControl />