how to engrave an arpeggio based on a chord of differing length notes?

[Kenneth Wolcott]

Hello;

  I have an interesting engraving problem I haven't seen before
(example png file attached).

  I understand how to handle the tuplet, the crescendo, the
decrescendo and the general polyphony, even the arpeggio.

  However, the arpeggio is based on a half note and a dotted half
note.  How to handle that?

  I'm using Lilypond 2.22.0.

Thanks,
Ken Wolcott