Combine Images for overlay

I try to do something similar to this post: related question

Now I try to combine several stencils. The combined stencil looks as expected, however the inverted group is either black or white, depending on the order of the group created. The result I get:

It seems that the grouping still takes some Blend-information of the childs, or maybe I just don't get the idea of the blends. Any Idea how I can achieve an overlay as in the old question but with several stencils?

Here are the images:

package application;

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.effect.BlendMode;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Rectangle;
import javafx.stage.Stage;

public class Main extends Application {
@Override
public void start(Stage stage) {
    Image original = new Image(getClass().getResourceAsStream("image.jpg"));

    Image stencil1 = new Image(getClass().getResourceAsStream("stencil.jpg"));

    Image stencil2 = new Image(getClass().getResourceAsStream("stencil2.jpg"));

    Image stencil3 = new Image(getClass().getResourceAsStream("stencil3.jpg"));

    ImageView iv = new ImageView(stencil1);
    ImageView iv2 = new ImageView(stencil2);
    ImageView iv3 = new ImageView(stencil3);

    iv2.setBlendMode(BlendMode.ADD);
    iv3.setBlendMode(BlendMode.ADD);
    Group stencil = new Group();

    stencil.getChildren().add(iv);
    stencil.getChildren().add(iv2);
    stencil.getChildren().add(iv3);

    Rectangle whiteRect = new Rectangle(original.getWidth(), original.getHeight());
    whiteRect.setFill(Color.WHITE);
    whiteRect.setBlendMode(BlendMode.DIFFERENCE);

    Group inverted = new Group(stencil, whiteRect);

    // display the original, composite image and stencil.
    HBox layout = new HBox(10);
    layout.getChildren().addAll(new ImageView(original), inverted, stencil);
    layout.setPadding(new Insets(10));
    stage.setScene(new Scene(layout));
    stage.show();

}

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