\version "2.19.80"
\include "oll-core/package.ily"
\loadPackage edition-engraver

\consistToContexts #edition-engraver Voice.Staff.Score

#(define (custom-dynamic-stencil grob)
   (let ((dyn (ly:grob-property grob 'text)))
     (cond
      ((equal? dyn "p")(set! dyn "P"))
      ((equal? dyn "pp")(set! dyn "PP"))
      ((equal? dyn "f")(set! dyn "F"))
      ((equal? dyn "ff")(set! dyn "FF"))
      )
     (ly:grob-set-property! grob 'text #{ \markup { \normal-text #dyn } #})
     ;(ly:grob-set-property! grob 'self-alignment-X -.75)
     (ly:text-interface::print grob)
     ))

customDynamics = \override DynamicText.stencil = #custom-dynamic-stencil

\layout {
  \context {
    \Voice
    %\customDynamics
  }
}

\addEdition custom
\editionMod custom 2 1/4 Voice \once \customDynamics
\editionMod custom 3 0/4 Voice \customDynamics

\repeat unfold 3 \relative { c''\pp b\f a\mf g\fp } \\