You can exclude expressions individually from alignment by adding the keyword EXCLUDE to the description text in the expression designer dialog.
This can be helpful if you need an unusual placement of an expression which at the same should be taken into account for visual score balancing.
Similar to the "EXCLUDE" feature, you can add "FORCEINCLUDE" to the description text of an expression and it will be included even if it is huge and far above/below a staff.
By default these expressions would not be taken into account for vertical alignment and/or spacing.
Image 1: EXCLUDE in the description text