I am writing a choral work with two staff labels, SA and TB. In system 3, the SA staff needs to split into two staves because it becomes polyphonic, resulting in three staves: S, A, and TB.
How can I temporarily change the staff label so that:
Sounds like a job for divisi. (Make sure that you’re using Section Players, not Single Players, in Setup mode.)
Create one Soprano Section Player. Relabel it as “S A”. Enter the music in two voices.
Create a Divisi point at the start of System 3. You can specify the labels for the Divisi staves, and hide the “original” labels. (You’ll also get nice little arrows showing the singers what’s going on.)