That was exactly my point, you know that you’re replaced the old one with one that has a different serial number, therefore you assume it must, and want it to, take the same place in the list of data that’s sent to emonCMS. (Because that’s the pertinent point here.)
Precisely, managed by you. [My emphasis]
If the sketch can always assume that a sensor that has gone missing has gone forever, and the first new sensor it sees is a replacement for that, then yes, it’s easy to manage that situation. But what if you’ve added a sensor, and in the process disturbed an existing one and cause it to fail? What if two have failed and you replaced both, at the same time? You’ll end up doing quite a bit of head-scratching until you’ve found, buried somewhere in ‘Resources’, the algorithm that describes what the sketch has done.
Anyway, this has gone off-topic.