How can I add a file to the playlist of VLC when it's allready in use

All my mp3 files are listed in a Excel Workbook
I use it to organise playlists for VLC.exe
I know how to throw VLC with the chosen songs. (use the right button in the example)
I know how to discern if VLC.exe is already opened.
But I do not know how to add a song to the playlist in case VLC is in functioning.
Someone has a idea?