Assembling a complex film

Dealing with a complex documentary film on environment, I used individual Timelines to edit each monothematic subject and finally assembled (moved) all Timelines into one single timeline for delivery (called Delivery). Each Timeline has one video track and four audio tracks (ambience, music, voice-over Italian, voice-over English). The problem: I need the Delivery timeline to keep the individual four audio tracks available in each of the Timelines used to build the complete film. Instead, when moving each Timeline to the Delivery timeline, the four audio tracks are mixed into one single audio track.
Could you please suggest how to deal with that issue? Thank you very much for your help.

Using DVR 15.3.1 + HP-Laptop i7-8565 1.8GHz 16GB + Nvidia GEFORGE + Win 10

Guess I found the solution. Edit Tab: use "Decompose compound clips on edit" when moving individual Timelines to the Delivery timeline should do it. . Thank you.