Single stave or two staves for an oboe / cor anglais part?
I am transcribing for the first time a 1930 manuscript which involves transposing instruments, and I'm unsure how to tackle the task.
In the manuscript, a single stave has been used to represent both the Oboe and the English Horn (Cor anglais) [Fig 1].
This means that when there's a change of instrument, the key signature changes [Fig 2].
Must I simply create two separate staves for the two instruments, and then extract both staves when creating the part for the oboe player?
The red ink in the manuscript was used to indicate "alternative instruments", which adds to my confusion....