Credit for this tip goes to editor Peter Teschner.
This tip was so perfect that I will be stealing it in the future.
Normally, after a preview temp dub, I would ask for and import LT/RT DME [DIA/MX/FX] tracks to place into our timeline.
One thing that had always bothered me was dealing with cleaning up the BG tracks for subsequent changes with the hard fx built into the tracks. I would just have to spend far more time to make it work.
Peter said that he would bring in a mono dialog track, mono hard FX track, mono BG track and stereo MX tracks. That way you could extend BG's without having to deal with the hard FX being tied.
Depending on the mix and how much spatial work was done, I would consider bringing in LT/RT dialog tracks to maintain the imaging and still be within the 6 track footprint or bring in LT/RT of DIA, BG, Hard FX & MX which would extend out to 8 tracks.