Hear me out on this one..
Starting at 1:10 out of 7:15 of My GIft To You by Korn,
When the lyrics kick in at 1:13, this part will be Roswaal singing, any lyrics from here on of "can you feel the pain?" and "can't you feel the pain?" will be Puck, any background audio of "aaaa" or "AAAHH" is ofc Subaru.
Going all the way to 4:17, this is Subaru's lyrics(tbh should be petelgeuse now but oopsie :) ) when "Just to see through your eyes" gets repeated, there's like distorted voices that'll be roswaal and pucks' voices during subaru's part.
At 4:55, it'll smoothly transition to Petelgeuse saying, "I hate you, can(t) you feel the pain!?"
Everyone at 5:54 starts singing the lyrics, with petelgeuse and Subaru switching off, doing the "can't you feel the pain/can you feel the pain", with puck singing the lyrics now, and Roswaal doing the "aaa" or "AAAH" sequences. End of song :) (this was long) I suppose you can also change lyrics around, considering there is swearing, and to make it suit each characters' role of lyrics.