In your example of 4 choruses:
Set the number of Choruses to 4

Melody set up:
1) Load the melody instrument on your preferred track. This can be an instrument or a Melodist track generated by the Melodist feature. In my test, I used the Melodist feature and loaded onto the Melody Track.
2) Open Bar Settings: Change the Chorus# selection from All Choruses to Chorus #2
3) Mute the Melody Track (or whichever trach you are using for the Melody)
4) Change the Chorus selection from Chorus #2 to Chorus#4
5) Return the Melody Track to normal.

The Melody should play through chorus #1 mute for Choruses 2 and 3 and play on Chorus #4

Soloist Set up:
1) Load the Soloist instrument on your preferred track. This can be an instrument or a Soloist track generated by the Soloist feature. In my test, I used the Soloist feature and loaded onto the Solo Track.
2) Open Bar Settings: Change the Chorus# selection from All Choruses to Chorus #1
3) Mute the Soloist Track (or whichever trach you are using for the Soloist)
4) Change the Chorus selection from Chorus #1 to Chorus#2
5) Return the Return the Soloist Track to normal.
6) Change the Chorus selection from Chorus #2 to Chorus#3
7) Mute the Soloist Track

The Soloist should be muted through Chorus#1, play through Chorus#2 and be muted for Choruses#3 and#4

Neither the Melody or Soloist should play on Chorus#3

BIAB 2025:RB 2025, Latest builds: Dell Optiplex 7040 Desktop; Windows-10-64 bit, Intel Core i7-6700 3.4GHz CPU and 16 GB Ram Memory.