You can install our site as a web app on your iOS device by utilizing the Add to Home Screen feature in Safari. Please see this thread for more details on this.
Note: This feature may not be available in some browsers.
From within the Tesla mobile app on your phone, click on the Security link, then click on Manage Drivers. From there you can add her and it will send a link for her to use. I think you can only have 2 drivers per vehicle at a time.