The command 'ReportChildDevices' is called each time the device is starting.
You have to report all the child devices which are available, the report has information about the type of child device, room, the internal id (as you will manage it, NOT pluto).
Ex: [internal id] \t [description] \t [room name] \t [device template] \t [floorplan id] \n
The internal id will be available as device data 'Port/Channel Number'.
Once you have sent your report as an answer(event) to the command, you will get all the child devices.