I tried that, but had problems. I could copy and paste only if the group was closed. Then once I had repositioned a copy near where I wanted it, i could open it and use the snap lines for positioning it exactly in line with other objects. So far not a real problem; I just had to try things until I found that this works. The problem is that when I export the diagram as a png, the gray boxes around the groups go with it and mess up the display. On top of that, i thought maybe I should ungroup them before exporting, but nothing happens when I try that. I draw a marquee around a group, select ungroup, and it's still grouped. There must be a fix for this.