From what I see, it’s not yet possible to vary the number or staff lines in the same instrument during a piece
No, you cannot vary the number of staff lines for an instrument, but you can give the player multiple instruments with different numbers of staff lines. (We would also like to make it possible to change the number of staff lines for an instrument over the course of the piece in future, too.)
As Daniel mentions, you could assign the player more than one custom instrument, and then merry change between them at system breaks. Should appear relatively seamlessly, even if you have to do a little more work on the back end.
Thank you @dspreadbury, I will do my definitive switch to Dorico once this feature will be implemented. So far, yet studying it.
I Just saw the incredible version 5 update. Great job!
Though it was good enough to get me through, the instrument change solution is still only a partial one. In this passage (from the piece that prompted the OP), the piano left hand switches between approximate and definite pitches:
Note that the braces at the start of the system are wrong: this is a single piano, and the two staves should be grouped with a single brace. The instrument-switching approach required me to break the two hands into separate groups, and AFAICT there’s no workaround for that.
In the long term, it seems like the “indeterminate pitches” switch needs to be per-staff, not per-player or per-instrument. It may be too esoteric of a problem to solve, but that would be the ideal approach.
In the meantime, three cheers for the new instrument editor!
Update: It just occured to me to simply try dragging the brace in the graphical editor, and lo and behold, it works! TIL.
So: awkward as heck, totally violates the “accurate semantics with visuals layered on top” design philosophy of Dorico, but apparently the current feature set really is sufficient for my esoteric problem!
I think that since more and more users are asking for this dynamic staff line change, the Team will implement it soon or later. Years ago, I was the only one to ask for that.
Cool solution, btw!