Normally when adding photos to Lightroom, I "Copy as DNG" from my camera's SD card to my external hard drive. Recently someone gave me a DVD containing over a thousand images in JPG format, which I added to my catalog. Unfortunately, without thinking I went with the default import method, which was "Add." This means the photos were not copied to my hard drive, but just added to the catalog. I then went through all the photos and rejected the ones I didn't need.
Now that I've realized my mistake, I want to copy the files to my external hard drive—but I don't want to re-import all of them and go through the whole review and reject process again. I want to just copy the images that are already in the catalog, the ones I imported and didn't reject. I can't find any way to do this in Lightroom. Is there something I'm missing?
I know I could just keep things as they are and put the DVD in when I need to work with these images, but my computer doesn't have a built-in DVD drive, and plugging it the external drive means unplugging something else to free up a USB port.