(d-AddLowestUpMajor3)
(d-Copy)
(d-CursorToHighestNote)
(d-RemoveNoteFromChord)
(d-MoveToStaffUp)
(d-SelectionToEmptyMeasure)
(d-Paste)
(d-MoveCursorLeft)
(d-CursorToLowestNote)
(d-RemoveNoteFromChord)
Seems to work pretty good (maybe not in all circumstances, still with the notes having to have their duration changed manually, but he cursor is left in the upper staff now allowing for quicker note duration change). So just two keypresses (i.e. "a,3" for a Major third, "e,5" for a Perfect fifth; Of course there are many options for keypress shortcuts that a person finds most convenient for their own set-ups).
Rain