VLC 2.x.x used to have the option --playlist-enqueue to add a file to the existing VLC Playlist. VLC 3.0.4 no longer has that option

$ vlc  --playlist-enqueue ~/Music/John_Mayer_Daughters.opus 
VLC media player 3.0.4 Vetinari (revision 3.0.4-0-gf615db6332)
vlc: unknown option or missing mandatory argument `--playlist-enqueue'
Try `vlc --help' for more information.

Running /Applications/VLC.app/Contents/MacOS/VLC with arguments will result in another instance of VLC being created.

$ vlc ~/Music/John_Mayer_Daughters.opus 
VLC media player 3.0.4 Vetinari (revision 3.0.4-0-gf615db6332)
[00007fbacb531620] main interface error: no suitable interface module
[00007fbacb500980] main libvlc error: interface "(null),none" initialization failed
[00007fbacb500980] main libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.

There does not seem to be any setting for VLC to run in a single instance only.

Question

How can I:

1. Add a file into VLC's playlist from the command line?

2. Do the above without launching another instance of VLC?

To add a file to VLC playlist from the command line (without starting a new instance) use the following syntax:

open -a /Applications/VLC.app/Contents/MacOS/VLC <your_media>

To prevent VLC from autoplaying the media you just added, go to Preferences > Show all > Interface > Main Interfaces > macosx and uncheck the box "Auto-playback of new items" below the Behavior subheading.