I discovered a new Score Editor function!
Just a small clarification: not only grand staff, but a single staff and any system.
I wouldn’t use “single staff” because if it’s part of a system, that single staff will not be moved to the next or previous page. The whole system will be moved. Maybe a better word (for Grand Staff / System) would be “music line” or “music row”. Eh, now I’m talking too much.
First I wrote : “Not only grand staff but any system”
Then I edited my post to emphasize that this function also works when a score contains one single staff, thus created from one MIDI track.