Nope.  I was overthinking it.  For once, the easy answer actually works.

Here's the previous animation with different settings for the chain length handling.  The start and end stay in place and the chain follows the markers.  I'm surprised.  :laugh:

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Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.