If I understand correctly what you mean, I was in the need of the same thing.
Was possible for me, by the next method.
Add it a SEND COMMAND plugin to my playlist with a EVENT - FIXED EVENT for program it at certain time.
The play list order would be something like this
EVENT - FIXED EVENT for time initialization of the stream
SEND COMMAND plugin with the command to play a stream from the internet.
the command itself to play the srteam in the play list.
PLAY 1-1 [URL] "https://SERVER.REPLACE.net/hls/live/2015530/dwstream104/stream04/streamPlaylist.m3u8"
