Never mind, found a solution on this wonderful forum already. I can do the trick with the F5 bar.

Quoting Jazzmandan

Topic: Using F5 (Bar Settings) to tell who to play what and when in BIAB
Author: Dan (aka Jazzmandan)
Description: Alway felt this was one of the top newbee questions, so I put together this video. A simple demo which shows how to use F5 (Bar Settings) to have different instruments step into different parts of the song. Example is done with Autumn Leaves having different RT soloists playing at different times (including the intro, choruses and specific bars) and leaving room for my vocals and solo to come in.

Link:
http://www.jazzmandan.com/Video/F5%20Bar%20Settings.mp4

If there are any other ways like with the soloist generator I would be happy to hear of them.

Jazzy holiday greetings,

Jazzer Phil