Download the Circle Home app onto the second Admin's device.
Connect that second device to the home Wi-Fi network that has Circle.
Launch the Circle Home app from the second device. After loading, the Enter Passcode screen should appear (see image below).
Tap "Resend code." An SMS text message with the new passcode will be sent to the original phone number used to setup Circle. NOTE: You must have access to the device with the original phone number used to setup your Circle.
Enter the passcode to link the new admin’s Circle app to the Circle device.