It’s not unusual to use two staves to notate cello music due to the range of the instrument, lower staff would be in bass clef and upper staff in tenor or treble clef. It doesn’t seem that Dorico supports this yet (v 3.5.0). I did try the advice in this thread https://www.steinberg.net/forums/viewtopic.php?f=246&t=194441 but couldn’t get it to work for me.
There was a note there that using a solo cello line and adding staves
to it should work, but it doesn’t. Putting an extra cello into the player (perhaps I’m doing it incorrectly) doesn’t seem to help either. The attached file shows the one player two instrument version, but the extra staff on one solo player looks the same.
Thanks for any advice!