Creo Interactive Surface Design (Style) > Curves > Mirroring Curves > About Mirroring Curves in Style
  
About Mirroring Curves in Style
You can create a mirror of curves without leaving Style. You can mirror any type of curve across a datum plane that is used as a mirror plane. You can create any number of curves in a Mirror feature.
The Mirror feature is dependent on the original curves. When you change the original curves, the corresponding curves in the Mirror feature update.
You can break the dependency of the Mirror feature if you convert the mirrored curves to free curves.