How to get there
From the 
Menu, choose Scoring and
Arranging, and then Piano Reduction.
What it does
The Piano Reduction plug-in helps you to
easily condense a number of staves into a piano grand staff. The piano
grand staff will be added to the bottom of the staff system.
- [Staves].
Select the staves in your document to be included from this list. Command-click
to select multiple staves.
- Split
Point. Set the split point for the piano staff.
- OK
· Cancel. Click OK to make the selected changes. Click Cancel to
dismiss the dialog box without making any changes.
