HomeKit accessories, including Elgato Eve accessories, are setup with an iOS device — for example, your iPhone. To share your Eve accessories with other devices such as your iPad, you can set up other iOS devices using the same Apple ID as the master iOS device, and iCloud will sync the HomeKit setup across all of them.
After that, Eve will automatically be able to use the master device’s setup. To enable iCloud syncing of HomeKit data, you need to enable the iCloud keychain on all devices.
Please be aware that sharing your HomeKit setup with other devices with the same Apple ID does not work if there is already a Home on the second iOS device. Please remove any additional Homes before beginning setup.
HomeKit assumes that you have activated both iCloud and iCloud keychain on all your iOS devices. Once you have any service that is part of iCloud (such as family sharing, syncing of calendars, contacts, reminders, iCloud Drive) set up on your iOS device, iOS assumes that you might want to use your data, including HomeKit data, on another iOS device as well. To securely access any HomeKit accessory from any vendor, the iOS device needs a secure access token that gets negotiated by entering the HomeKit setup code when pairing during initial device setup.
The Keychain and the iCloud Keychain represent system-wide storage for private data such as passwords, credit card information, access tokens, and more. The iCloud Keychain is also a means of securely sharing HomeKit access tokens across your iOS devices. This security is all built into iOS, with no user- or developer-configurable options