You can use multiple Rest devices in your home. When you log into your app you will be brought to an Available Rest screen where your app will display all Rests within Bluetooth range (20-30 feet). Tap on the Rest you'd like to connect to and you'll be brought to the main remote screen.
To reconnect to a different Rest, you will have to disconnect from one to get back to the Available Rest screen. When connected, tap on the down arrow next to the Rest name at the top of the remote screen to disconnect and select a different Rest.
Be sure to name your Rests with unique names to make them easy to identify!