Question about modding player characters and song variants

[PSI3x]

I’ve been looking through the slight amount of documentation on modding in player characters and there’s something I’d like to ask: Is a way to specify somewhere, such as the metadata json for the specific song, for a character to use the default instrumental and opponent .ogg files in their version of the song?
If not, is this a possible planned addition? I believe it would be very beneficial to add from a filesize optimization, as I believe it is best to not include arbitrary copies of the same sound files for both the default instrumental and opponent voices.