It could be parented to the eyeball, with the magnet set to deform the head as well as the eyeball and the magnet value set to zero for the eyeball itself, perhaps.  A trick like that has been used to have one actor deform another in animation, IIRC.  Fist puches a face, deforming the latter only when the magzone parented to the fist makes contact with the face.  Something like that.

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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.