Alignment help

[Rajesh Baskar]

Hi,

I'm trying to replace some of the notes with a question mark and I achieved 
this with this group's help sometime back. Here is the Lilypond file -

    \version "2.22.0" \language english
    questionMark = \markup     {\fontsize #7 \with-color "#6A00F4" "?"}
    \header {tagline = ""}
    \score {\new Staff \with {\remove "Time_signature_engraver" }
            {\set Staff.midiInstrument = #"Acoustic Grand Piano"
             \key c \major \time 5/1 \clef bass
             g,1
             \omit Accidental \override
             NoteHead.stencil = #(lambda (grob)
                                   (grob-interpret-markup grob questionMark)) a,
              b,
              c
              d \bar "||"}

            }


This generates a staff with the question mark in an ascending pattern as shown 
in this image.

[cid:9b97dfb1-a009-46b4-83a4-8b98eb74d53b]

But I want the question mark to be within the staff, like the below image.

[cid:1a71965f-da9d-419e-bf96-02cfd55c95db]

Can someone help me with aligning the question mark?

Thanks,
Raj