Midi setup for string composition

I could do with some help in how to set up midi for string composition
ie 5-6 instruments

I have CB Elements 9 + steinberg symphony installed

My working method up to now has been to record the theme and then add the orchestration layers by hand but this is very limited.

Ideally I’d like to work with all the different instruments in one part
This seems to be happening in the wonderful tutorial from JUNKIEXL
https://www.youtube.com/watch?v=mdHbWSYm3f0&list=RDmdHbWSYm3f0
Composing For Strings Pt.1 at for instance 22m 30secs

Can anyone give me a recipe for configuring any of this or point me to a tutorial or two that shows how to set it up?

W10 i7