Add instrument groupings and auto-sorting to the add instruments dialogue
Adding this feature would be most useful for adding a new part to an existing large score.
There should be a checkbox on the instrument addition dialogue to offer to snap new instruments into their default position in the score, rather than add them to the bottom and manually need to be placed.
In a related vein, it would be quite nice to add another level of depth on the score side to group our instruments, like what we have on the left pane of the instrument selection panel. That way, we could move all vocal parts to the top of the score (for example), rather than bubble them up one by one.