Currently we are working on a bug that will not let you add more CD (non-karaoke) songs to a target folder in the external hard drive that has only the CD (non-karaoke) songs and is converted (by pressing the CONVERT button) to _songs folder. 

So if you already have CD (non-karaoke) songs in a folder of an external hard drive and the folder is converted (by pressing the CONVERT button), it is not possible for you to pree MODIFY button to bring up the song files on the target side in order to add more songs.

A temporary measure is to add at least one karaoke song (MP3 and MCG file) in the folder of the external drive before converting.  Then pressing the MODIFY button will bring up the song files (both non-karaoke and karaoke) on the target side without problem for adding new songs.

New version of MCG Manager with the bug fixed will be uploaded shortly