Again, sorry for the long silence, Shaun! I've now finally finished moving to the new house, and I'm now writing from my new home office. I'm now going to be able to spend much more time in front of my Mac now. 😄
In any case, you found exactly the right code. As you can see, changing the ID is not prohibited; at least if you're making sure that the new ID contains only alphanumeric characters (plus "_" and "-"). So I don't think anything speaks agains simply changing it, now that there's no server involved.
Have you tried that already in the meantime?