Using the Pulll mode you can multistream and create a livestream pulled from an HLS URL.
See the supported protocols for Pull mode in Castr here.
How to Switch to Pull Mode and Use the HLS Live Source
In your Castr Dashboard:
Create a new Live Stream or Multistream project
Select the Pull streaming mode
Under the Pull Source section, paste your HLS URL > Save
You will be able to stream HLS to multiple social platforms. If you need further help, please contact Castr 24/7 support.