Something I would find useful for mockups would be alias staves. That is, staves whose content is mirroring that of another stave, and each change in the original staff is immediately reflected on the alias staff.
What should be excluded from this exact copy would be the instrument assignment, and the expression map. This way, one could write, say, the Violins I part in a staff playing with Ensemble Strings A, and have a layer in an alias staff playing with Ensemble Strings B.