Convert Playlist to MP4

[ManUBlueJay]

I am trying to edit a movie using VLC playlist start stop. It works to play the playlist. It jumps to the correct time but I would like to convert it to a MP4 file. so it can be used without VLC
It does the 1st segment but when it comes to the second segment it wants to overwrite the file.
Is there a way to make playlists append to the main file
Here is a script of my Playlist
#EXTM3U
#EXTINF:6885,My Movie.mp4
#EXTVLCOPT:start-time=1
#EXTVLCOPT:stop-time=60
My Movie.mp4
#EXTVLCOPT:start-time=120
#EXTVLCOPT:stop-time=180
My Movie.mp4
#EXTVLCOPT:start-time=360
#EXTVLCOPT:stop-time=240

[Rémi Denis-Courmont]

You need the --sout-keep flag

[ManUBlueJay]

Thank you for that.
Like I said I am very new, how do I accomplish that.
Thank you in advance