If you set up a sequence as an 8 channel multitrack with your stereo mix on tracks 1 and 2 and the surround on 3 to 8 then use these export settings:
I've never done this but it is a good place to start.
So you're aware I have a 2.0 wav file and second wav file that's 5.1 (both supplied by the projects Sound Designer). I have set-up a new sequence with one video track (final video) and two audios tracks (1 x 5.1 and 1 x 2.0). But when I attempt to export the file via File>Export>Media>Audio>Audio Channel Configuration I cannot export both 2.0 and 5.1 within the same ProRes file.
Can you give any guidance in terms of getting past this so both 2.0 and 5.1 can be exported and included within the same ProRes 422 HQ file?