Can lilypond grace note beams be added to regular beams?

Question

I'm engraving Bach Invention 4 (D Minor) BWV775 in Lilypond and the existing score has grace notes (measure 37) beamed from a regular note:

My reading of https://lilypond.org/doc/v2.21/Documentation/notation/beams#manual-beams is that grace note beams can be in parallel but are seperate.

So my best attempt at present is:

a16[ d,-1] << { b8.-2] a16-. } \\ { b8. \grace { c32 b8 }} >>

which gives me:

Trying a beam into the \grace { } gives me unterminated beam error, so it appears grace notes are beamed seperately. I suspect there may be a different approach than using a seperate voice for the grace notes though.

Answer 1

I suppose you do not really want grace notes there but rather something like

\new Staff
{
  \time 3/8
  a''16 d''
  <<
    \mergeDifferentlyDottedOn
    {
      \override Beam.length-fraction = 0.70
      \override Stem.length-fraction = 0.9
      \override Beam.beam-thickness = 0.37
      b'32[ \tiny c'' b'8]
    } \\
    {
      b'8. a'16
    }
  >>
}

Answer 2

Here's a slightly different way to do the same thing using \magnifyMusic and force-hshift. The main advantage (beside being smaller) is that you only have to manually adjust one thing.

\new Staff \relative a'' {
  \time 3/8
  \mergeDifferentlyDottedOn
  a16 d,
  <<
    {
      \override NoteColumn.force-hshift = 0.4
      \magnifyMusic #2/3 { b32[ c b8] }
    }
    \\
    { 
      b8. a16 
    }
  >>
}