Hypothetically, a Python script should be able to mirror selected hairs, if there isn't a built-in tool for this (I know there's no such tool in Poser 5).  I don't think any such script currently exists, however....

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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.