In Setup mode, you should only have four section players, one for each instrument.
Then, where you want the division to change (or at the start of the piece), right-click on a staff, select Staff > Change Divisi… and then click on Add Section Player. You can then either do this for the other staves, or select the Divisi change and Alt-click the other staves (at the same rhythmic position) to duplicate the same divisions.
If, later in the piece, you want to restore unison, right-click the staff and go to Staff > Restore Unison.
Also note that you can condense these staves onto one staff, which may be useful if the parts are almost unison, or in rhythmic unison.
See this article for more info: