Register the Second Face ID to use iOS 12 Multiple Face ID; On the Face ID & Passcode window tap on Set Up an Alternate Appearance. The process needs to be repeated as you did while registering for the first face. Once the face is registered, you can

When the iPhone X first launched, people got were for Face ID, the new feature that allowed the user to unlock their device with just their faces. However, there was one annoying limitation when it came to Face ID: you could only set up one face.

How to Register Two Faces in Face ID on iOS 12 When the iPhone X launched last fall, the phone’s nearly edge-to-edge display crowded out the Home button’s fingerprint sensor.