Thanks again, Shane & Julian.
Funny after taking Ownership of Packages & copying the Cat_Mum_Files into it, they were already there.
But then I'd just done a successful dism.exe /online /cleanup-image &c pointing to a mounted newer larger Win 10 .iso (2.84 GB) that I'd just got.
The penny should've dropped.
I'd been trying, unsuccessfully, for the better part of a week, to get dism to run off the original smaller Win 10 .iso (2.41 GB) that I used for the install.