Move slur for acciaccatura

[Nick Payne]

The slurs on the acciaccaturas in my score are all defaulting to above the
stems of the grace notes, even when the grace notes are on or above the
middle of the stave and their stems are up. How can I move the slurs to
appear beneath. I tried using

                        \once \override PhrasingSlur #'direction = #DOWN
                        \acciaccatura { d16[ e16] } d8 c\> d2\! ~

But I still get the slur above, as shown in the attached PNG

Nick Payne

acciaccatura.png
Description: PNG image