Tip: Change a single player to a section player to allow divisi passages

https://blog.dorico.com/wp-content/uploads/2022-08-02-Change-Single-to-Section-Player_1080.mp4

Single players can hold multiple instruments.

Section players can divide.

Single players cannot divide.

Create a new section player, and drag the instrument from the single player onto it. Its music moves with it. The single player—which is now empty-handed—can be deleted.

Now you can create a divisi staff for the section player.