Any way to limit a sound file to specific stages of sex?

[Fomebs]

I've read this post from long ago that states there used to be folders named 2 and 3 in lovers sounds -in addition to 1,4 and 5- and that they played during (or only in the beginning of?) stages 2 and 3.

 

I have tested if this still works, and apparently it does not. Is there an easy way to make this (making stage-specific sounds) happen, perhaps through some tweak to the Lovers with PK esp?

 

Edit: On a second try with another voice set, it worked. That is, a voice file i put in only folder 3, played at stage 3, among many from folder 1. So, I suppose folder 3 & 2 files play only very rarely in their corresponding stages, while files from folder 1 play at all three stages (similar to what was said in that post). So, does anyone know how to make stage 3 exclusive to folder 3 (or perhaps, increase the frequency of folder 3 files that play at stage 3)?