Apply blending mode to images in group with a script

I have a long document with many photos. These photos are in groups along with their captions. They currently have the blending mode "Luminosity" applied, but I want them to have "Normal" applied. 

I found this script which does exactly what I want with a little modification. But it only works on regular rectangles. If I put the rectangle in a group, the script no longer works on it. Therefore the script doesn't work for my documents because they all have images within groups. How do I modify the script to look within groups?

Here's what I have so far:

// the main function
var main = function() {
  var doc = app.activeDocument; // get the current document
  // loop the pages
  for (var i = 0; i < doc.pages.length; i++) { 
    var page = doc.pages[i]; // isolate the page
    // loop all rectangles
    for(var j = 0; j < page.rectangles.length;j++){
      var rect = page.rectangles[j]; // isolate a rectangle
      // test if there is an image inside
      if(rect.images.length > 0){
        var image = rect.images[0]; // isolate the image
        // asign a random color from th swatches
        image.transparencySettings.blendingSettings.blendMode = BlendMode.NORMAL;
      } // end if image
    } // end loop j rectangles
  } // end loop i pages
} // end of main
main(); // run it

Thanks in advance!