Adding a property already in the Essential Graphics panel adds a mirror
(EgKind::Mirror: own name and place, one value in the comp and in every
instance; editing, reverting or pushing either acts on both). A property
control can also drive further properties of the comp (links follow the
main property both ways and take instance values). essential.addMirror,
essential.linkProperty, essential.unlinkProperty; panel badges and menu;
ExtendScript addToMotionGraphicsTemplate(As), canAddToMotionGraphicsTemplate,
motionGraphicsTemplateName, controller count/name and
exportAsMotionGraphicsTemplate.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>