Received your method, very good, thank you.
If you're adjusting the mesh in Headshot, make sure you have symmetrical checked. https://manual.reallusion.com/Headshot_Plugin/ENU/Headshot_Plugin_for_CC/1.0/ID_SA_Pro.html
Modify Tab > Edit Mesh > Mirror Copy https://manual.reallusion.com/Character_Creator_3/ENU/3/Content/Character_Creator_3/3.2/08_Creating_Custom_Assets/Symmetrizing_Vertices.htm