Options for different instruments on a single grand staff
I'm trying to notate different instruments on a single grand staff, but it seems that this is not supported.
What I can do is either add a single instrument at document creation with a grand staff, or else have two instruments on two staffs (which I could then tediously link, measure by measure, which would be close-enough).
Why would I want to do this? Because the "instrument" in this case is the human voice, broken into a baritone part (lower staff), and a soprano part (upper staff) formed from the harmonics of the lower part (this is called "polyphonic overtone singing"). The lower staff sounds mostly like a human voice, but the upper part is more like a flute. And, they need to be labeled separately. So: two instruments, one grand staff.
Since I'm somewhat new to MuseScore, I'm hoping I'm just missing some way to do this, but I haven't been able to find any. If it is indeed impossible, does anyone have thoughts on what I can do instead?