Comunication between controllers loaded as child

Question

I've been developing an application with following structure: App structure

It has a main.fxml (menubar and contains anchorpane), the anchorpane is changed in it content by vistanavigator class that call maincontroller and pass the content1.fxml loaded as a node.

I want to pass parameters between content views when the view is changed from content 1 to content 2, i've been trying how i can do this but i dont know how.

Here is the code:

Main Class

public class Main extends Application {



@Override
public void start(Stage stage) throws Exception{
    FXMLLoader loader2 = new FXMLLoader();
    Pane ventanaprincipal = (Pane) loader2.load(getClass().getResourceAsStream(VistaNavigator.MAIN));
    Scene scene = new Scene(ventanaprincipal);

    MainController mainController = loader2.getController();
    VistaNavigator.setMainController(mainController);
    VistaNavigator.loadVista(VistaNavigator.VISTA_SESION);
}

public static void main(String[] args) {
    launch(args);
}}

MainController

public class MainController implements Initializable {

    @FXML
    private AnchorPane contenido;


@Override
public void initialize(URL url, ResourceBundle rb) {

}


public void setVista(Node node) {
    contenido.getChildren().setAll(node);

}}

VistaNavigator class

public class VistaNavigator {


public static final String MAIN    = "main.fxml";
public static final String VISTA_SESION = "sesion.fxml";
public static final String VISTA_INTERFAZ = "interfaz.fxml";

private static MainController mainController;

public static void setMainController(MainController mainController) { 
    VistaNavigator.mainController = mainController;
}

public static void loadVista(String fxml) {
    try {
        FXMLLoader loader = new FXMLLoader(VistaNavigator.class.getResource(fxml));
        Node ventana=(Node) loader.load();
        mainController.setVista(ventana);
    } catch (IOException e) {
        e.printStackTrace();
    }
}}

Content1 controller

public class sessioncontroller implements Initializable {



@FXML
private TextField usuario;
@FXML
private PasswordField contrasena;
@FXML
private Button iniciobutton;
@FXML
private Label error;


@Override
public void initialize(URL url, ResourceBundle rb) {



}

@FXML
private void inicio(ActionEvent event){


    if(sesion.getusr()!=null && sesion.getemail()!=null) {

            ////HERE I WANT TO PASS VALUES TO CONTENT2.FXML
            VistaNavigator.loadVista(VistaNavigator.VISTA_INTERFAZ);

    }else {
        error.setVisible(true);
    }

}
}

The question is different than other because the content are changed in same scene as children anchorpane.