#(define (pagebreakone grob)
            (let* (
                   ; have we been split?
                   (orig (ly:grob-original grob))
          
                   ; if yes, get the split pieces (our siblings)
                   (siblings (if (ly:grob? orig)
                               (ly:spanner-broken-into orig) '() )))
          
             (if (and (>= (length siblings) 2)
                       (eq? (car (last-pair siblings)) grob))
               (ly:grob-set-property! grob 'control-points '((0 . 0) (5 . 5) (10 . 15) (15 . 0))))))

\relative
{
	\override PhrasingSlur #'after-line-breaking = #pagebreakone	
	c \( d e f | \break
	c d e f \) | \break

	c  d \( e f | \break
	c d e f \) | \break

	c  d e \( f | \break
	c d e f \) | \break

	c  d e f \( | \break
	c d e f \) |
}