Divisi string parts / adding an additional staff /instrument for only part of a score

Occasionally I want to divisi the strings and add an additional staff for a few measures to make it easier to read but when use "Split staff" it split s the entire score . Is there any way to do this for just a few measures? This feature could also be used to add an additional instrument for just a few measures which now requires adding the instrument for the entire score and if creating an album requires putting it in the first score as well.