A somewhat related set of features which, as far as I can tell, doesn’t (yet?) exist, would be an “explode to several staves” from one staff and vice versa (implode/combine several staves into one). I consider this a very important and useful function, particularly during the process of orchestrating where one likes to move things around a lot (working from a piano version, for instance), something I use all the time in Finale. Hope this is also in the works for the future.