Sorry, no, there is not a way to automagically add backlinks to the directory. There really is not a way to do this automagically and not be very resource intensive. It probably would be too bad to do a word by word search to find matches based on name when doing a post save. The really issue would be multiple word names. Ideally directory backlinks would be tagged somehow so they could be easily parsed from the page content. But, if you’re tagging something, at that point it is probably just best to manually add the link like any other link.