srt2hls - how to generate index.m3u8 from multiple inputs without re-encoding?

[LifelessMuffin]

Hi guys, I would like to transmux the 3 inputs (with different bitrates) into 3 individual playlists (high.m3u8; mid.m3u8; low.m3u8) which are then indexed into the master playlist index.m3u8. When re-encoding a single input as shown in the examples it works fine, the index,m3u8 file is generated along the other playlists (ABR). But how to achieve the same without re-encoding and with 3 inputs?
This is my script:

settings.root.max_latency.set(5.)
settings.clock.allow_streaming_errors.set(false)

input_a = input.srt(port=9000, mode="listener")
input_b = input.srt(port=9001, mode="listener")
input_c = input.srt(port=9002, mode="listener")

transmux_high = %ffmpeg(format="mpegts", %audio.copy, %video.copy)
transmux_medium = %ffmpeg(format="mpegts", %audio.copy, %video.copy)
transmux_low = %ffmpeg(format="mpegts", %audio.copy, %video.copy)

high_stream = [("transmux_high",transmux_high)]
medium_stream = [("transmux_medium",transmux_medium)]
low_stream = [("transmux_low",transmux_low)]

def segment_name(~position,~extname,stream_name) =
  timestamp = int_of_float(time())
  duration = 2
  "#{stream_name}_#{duration}_#{timestamp}_#{position}.#{extname}"
end

output.file.hls(
                playlist="high.m3u8",
                fallible=true,
                segment_duration=2.0,
                segments=5,
                segments_overhead=5,
                segment_name=segment_name,
                "/var/www/liquidsoap/hls",
                high_stream,
                input_a
               )

output.file.hls(
                playlist="medium.m3u8",
                fallible=true,
                segment_duration=2.0,
                segments=5,
                segments_overhead=5,
                segment_name=segment_name,
                "/var/www/liquidsoap/hls",
                medium_stream,
                input_b
               )

output.file.hls(
                playlist="low.m3u8",
                fallible=true,
                segment_duration=2.0,
                segments=5,
                segments_overhead=5,
                segment_name=segment_name,
                "/var/www/liquidsoap/hls",
                low_stream,
                input_c
                )