Thank you for responding.
The MS document you referred to was for Windows 7. The machine I am working on was born with Windows 8 (original OEM install) and later upgraded to 8.1.
I have taken 5 photographs which show the partition setup, the MR dialog and the final warning about overwriting (at that point I cancelled rather than continued).
Here is the partition setup (seen in Win 10 but I am certain it was the same in 8.1).
Here is the Macrium Reflect setup:
Note that the file to restore (the source file) is prefaced with drive name I:
After clicking "Restore Image" we get:
Note above that drive H: (450MB) has now turned up as part of the destination.
This summary (above) looks OK, but:
I took the warning above literally, believing drive I: to be the drive with the source file, and therefore cancelled out. However I am now realizing that what has become drive I: is probably not the 466GB source file drive, but rather the 450MB recovery partition seen in the first photo and later seen as drive H: in MR. The inconsistent shuffle of drive letters is what has caused the confusion.
Do you concur with that? Do you see anything else that should concern me before restoring the Win 8.1 backup image?
Thanks for your assistance.