In a situation like
\version "2.19.44"
\new Staff <<
\new Voice {
\voiceOne b'!1
}
\new Voice {
\voiceTwo bes'!2
}
>>
Lilypond puts the two accidentals first, then the to note heads side by side ("flat-natural-notehead-notehead"). Is there a way to obtain the ordering "flat-notehead-natural-notehead"?
Best
Lukas