How can I mirror a 3D sketch of an inserted part within a component?

 ~ Without having to create a new 3D sketch, convert entities, mirror the entities within the new sketch; then create another new 3Dsketch and convert the mirrored geometry from the previous sketch, since I don't want the old geometry in the new sketch? ~

I ultimately need the sketch to create a sketch pattern on a mirrored part. Catia would involve quite simply mirroring a sketch!!

Thanks