A unit shows the data of the devices on it. Add a device when you fit a second device, such as a sensor box, and move a device when you replace the hardware in another vehicle.
In the side menu, select Units > List View.
On the unit's row, select Edit.
The unit opens in edit mode with one card per device.

Select the card "Click here to add more devices", marked 1.
The Device Allocation dialog opens.
In Device List, choose the device. You can search by name, identifier, model or SIM number.

Select Add.
A card for the device appears.
Select Save.
The units list opens with the message "Unit updated sucessfully".
If the device you chose in step 4 already reports for another unit, step 5 asks first.

The question ends with a correlation ID. Quote it if you contact support@getgps.eu.
In edit mode, drag a device card to a new position, then select Save. The app keeps the order.
The device stays in your account and can go on another unit. Its earlier messages stay in the unit's history.
Select Preview at the top of the screen to check the sensor names and order for the unit you are editing. The unit card on the map shows the sensors in the same order. See Unit card on the map.
The unit's Log tab on the map records each device added or removed. See Services and Log tabs. Trips and reports for past days are recalculated for the new set of devices.