How do I add other people’s iOS devices to the lock?

You can invite people with an iCloud account to share control of HomeKit accessories in your home. All people in a shared home can see accessory updates and control accessories. You must be in range of your Schlage Sense Lock in order to add other iOS devices to your HomeKit home or have a home hub set up. For Encode Plus users a HomeKit Hub is required to add additional users to the lock outside the Schlage home application.The user you are adding does not need to be in range of the Schlage Lock, but does need to have an active internet connection to accept the invitation. 

For iOS 11.2.5 or later, follow these instructions from Apple here.