[DavidFW1960]

You are right, it does assume that.  And that certainly did happen (i.e. the whole skin folder was replaced) - at some point when I explicitly tested it.  I wonder if that is a general change, or an osmc thing?   I tested it a good while back, though, and can't say for sure I have tested that with matrix or not ( or later matrix versions at least).

I'd presume it's a general Kodi change (wonder what the reasoning was, though?) - but if the .originals are not removed on skin updates, it all becomes a bit trickier, because then how do I know whether or not it is grabbing the actual skin original files?

Well you could check if the skin file contains your mod lines (OzWeather section) and if not then assume they are the new oriiginals and overwrite the backups? Or even write the originals to the patcher folder and not store them in the skin folder. I guess the thing is those xml files *could* change in a skin update so you'd want to back them up if the xml file isn't your patched one.