To tackle this, the first step would be sitting down with paper,
formulating what new kind of problem we want, and figuring out
an algorithm to solve it, maybe a variant of the existing algorithm
to solve springs&rods problems (in lily/simple-spacer.cc),
or maybe an algorithm found or adapted from existing literature
in algorithmics. Then implementing, debugging and profiling it ...
Thinking about this in terms of Excel cells, where they can extend as far as possible as long as there are no contents in adjacent cells....
Might it be possible for the lyrics engraver to add something like a lyricPlaceholder grob into adjacent note columns that had no lyricText grob?
The extent of the lyricPlaceholder could be the negative of the extent of the lyricText in the current column.
The lyricText in the current column could be aligned in the opposite direction of the adjacent column.
To those who are more familiar with the layout engine than I am -- could this be a possible approach?
Thanks,
Carl