Huge thanks have to go out to @akbooer for helping me realise this idea, so for those of you that want to check your web dashboard and see instantly when your motion and door/window sensors last tripped - check this out.
Can you clarify one question, it probably sounds stupid, but, is the file only uploaded once and all devices share it or do I need to upload it for each device that I would like to see the info displayed?
Just the once, the same .json file is used by all instances of the same device .
I would recommend that before you upload the new one, that you download a copy of the original .json(s).
If you have any spercific questions about the Lua code side of things, it would be best to post those via the thread linked to above.