Very challenging composite

This is the second most complicated, time-consuming, and challenging composite I've ever done. I photographed costumed model Mona Rose and her sister, Annette, with a harp in Venice. Looking for an ultra dynamic background and something that's different than what's available in Venice, I chose the Kremlin Palace in Moscow. The difficulty, of course, was making the background show through the strings of the harp. When I first considered doing this, I enlarged the image of the models and the harp to see if this was even possible, and I thought, "No way. I'm not going to do that to myself!" But when I want to create an image that I think will be impressive, and I can see it in my mind, nothing stops me. So, I spent three hours making 53 separate selections (i.e. channels) using the pen tool. No selection tool in Photoshop is as precise as the pen tool. Each string was just a few pixels wide, so I had to be very careful not to obliterate those very thin lines. My settings for the shot of the models were 1/50, f/5.0, 2500 ISO, and I used a 16-35mm lens. My settings for the palatial room were 1/500, f1.8, 1600 ISO, and I took this with a 14mm Sigma lens.