I have a huge iTunes library of mp3s (tens of thousands of songs). I keep a backup of it on a separate drive + I keep my music on an SD card in my car. Since I like to keep my songs organized I'm currently in the process of editing/updating the songs' ID3 tags (adding artwork etc) + replacing some of my old mp3s that might have had lower bitrate/quality etc with new ones with better quality. However, since it's an ongoing process I'd still like to have the songs on my car's SD card up-to-date, but I don't want to copy and replace ALL the files on the card each time I wanted to update the songs on the card. I'd like to replace the files on the SD card only with the mp3s that have been modified in any way (and replace any old songs with the new ones). How would I do that?