When adding an entity from a component/platform, add_entities(devices, True) is used.
What does the True part represent?
Can’t see to find any documentation on this function.
If the second parameter is True, then the entitiy will immediately be updated (i.e. update or async_update is called) after it has been added, if the parameter is False then it will just follow the regular updte path, for example time based or triggered by an event.
Oh okay - thank you.
Not quite the answer I had hoped 
Hoped it was more like if the sensor already exists, then it was a matter of replace or add new - or something like that