I was able to change the score order of a single system by inputting negative numbers in TGTools Staff Manager.
1) There is a lot of trial and error to get the numbers right.
2) As soon as you move the staff manually, it snaps to the zero position.
3) Staff Manager has acted suspiciously for the last few versions of Finale.
My problems ranged from corruption to extreme bloat and slowness. (Again, I'm talking about the Staff Manager, not middle age!)