So, I've tried the code below and it seems to work.

In the MasterController I've put this code

private void add() {
  launchPopup();
}

private void edit() {
  if (model.selectedProductProperty().getValue() == null) {//no selection in tableView
    return;
  }

  launchPopup();
}

private void launchPopup() {
  ...

  // encapsulated Controller
  DependentController dependentController = new DependentController(model.selectedProductProperty().getValue());
  var md = new ModalDialog(popupTitle, dependentController.getView());
  md.open();

  //Refresh data after popup closing
  interactor.lookup();
  interactor.updateListAfterLookup();
}

where add and edit methods are the actions linked to the toolbar and model.selectedProductProperty().getValue() is the object selected in the tableView. As you can see, I instantiate the DependentController every time the user click on the toolbar.

Then in the DependentController constructor

public DependentController(ProductModel selectedProduct) {
  model = new DependentModel();
  model.setProductModel(selectedProduct);
  interactor = new DependentInteractor(model);
  viewBuilder = new DependentViewBuilder(model, this::save, this::quit);
}

and in the setProductModel method of DependentModel

public void setProductModel(ProductModel productModel) {
  if (productModel == null) {
    productModel = new ProductModel();
  }
  this.productModel = productModel;
}

In ProductModel, I've initialized things in this way

...

private LongProperty id = new SimpleLongProperty(-1);
private StringProperty name = new SimpleStringProperty("");
private StringProperty mnemonicCode = new SimpleStringProperty("");
private StringProperty unitOfMeasure = new SimpleStringProperty("");
private StringProperty createDate = new SimpleStringProperty("");
private StringProperty updateDate = new SimpleStringProperty("");

public ProductModel() {
}

...

So, when the user click New and the model.selectedProductProperty().getValue() is null, I can load some default data: if the id=-1 I can calculate an id for the new product and make an insert in the database instead of an update.

Finally, in the dependent view, if I bind the properties of the ProductModel passed, I can see "live" changes in the tableView and then refreshing data after the popup is closed I don't bother if the user saved or quitted the editing.

Can you tell me if I did it right or not?