Good question, @Shelley37. You can certainly add another user to your Ring devices following a couple methods. The suggested method is throughShared Users. This allows you to invite someone via their Ring account email address, in which they will gain access to the Ring device you invite them to. Shared Users cannot change settings, other than the alerts they receive on their mobile device.
The other method is simply by logging into the other mobile device with the same Ring account credentials, or as owner. This will allow for multiple mobile devices to control the Ring app and Ring device settings as the owner, and should only be used if you want two owner devices. These authorized devices can be controlled at anytime via the Ring app Control Center. I hope this helps! 