Awesome that you are looking to add an additional Plaato Airlock to your app. This process is super easy and quick, here is how๐๐ผ
Steps
Launch your Plaato App
Power on the additional Plaato Airlock you are looking to add and make sure it is in "Setup-mode".
In your App, click on the menu button located at the top right of the screen
Click on "Add new device" and follow the Airlock set up process linked here