Just curious which stem would breathing end up in? Its a chase scene that I had to adr entirely and so I have looped in breathing. I have it on a separate channel for mixing purposes but does the breathing end up in the dx stem? or would it maybe go into an fx stem.
Back when i used to QC feature mixes, M+Es would often be accompanied by an "options track": a mono track with nothing but the breaths and non verbal vocalisations. This makes the most sense to me, as it gives the dubbing house the option of using it or not, while keeping vocal stuff out of the M+E.
To achieve this, i'm guessing it'd be best to keep your breaths in the dial stem, but on separate "Breath Tracks" so you can also send them to an options track (rather than the M+E).
The small effort this takes can save so much time in dubbing!
Unfortunately I've never mixed on a big stage like 20th Century or WB,
But in my humble opinion, it really depends on if you're going to need it for foreign overdubs.
If overdubbing, it might be a good idea to place it in with the FX so it's there for the foreign dubbing team who then don't have to re-create it.
If doing an English only mix, I would place it on the dia stem.
To me, it makes more sense to put it on the dia, but I also like to take into account those later on the chain.