Re: Double-stemming question.

[Lukas-Fabian Moser]

Hi Hwaen,

> The single notes and triads merge correctly, but the
> four-note chords do not.

This seems to be a bug. The culprit is the combination of two notes a 
step apart (and you can see that they are aligned differently in both 
instances).

While I can't provide you with a solution right now, maybe the following 
minimal example helps:

\version "2.20.0"

\new Staff \fixed c'
<<
  { <f a> <g a> <g b> } \\
  { <f a> <g a> <g b> }
>>

Lukas

PS. As an aside: To be honest, I think that the triple-dots in the 
lowest voice, while perfectly correct, are overkill. Of course it's a 
matter of style and taste, but my feeling is that lots of composers 
(like Schumann for instance) would just have written a downwards stem 
without bothering to much about the mathematically correct length.