I'm using your plugin and it's great, in fact, it is the only related posts plugin that worked on my blog!!!
My problem is I would like to change the thumbnail's images manually: Often I use images directly from URLs and they are not shown as thumbnails. Also sometimes I publish posts as slideshows of images. In both cases there are shown default images as thumbnail.
Should be possible to change that (or maybe select an image from the library) manually, without putting a featured image on the posts?
Thanks a lot!