Welcome to the forum @public1
Changing source OS would be worth reading then. It’s from last month and adds a new technique.
What did you think of the other ones you saw while reading in any older posts? Are any workable?
EDIT:
I’m not clear what Duplicati has and now wishes to backup, as opposed to restoring which is easy.
When one starts dealing with VMs, containers, and hosts, it’s confusing what the exact situation is.
EDIT 2:
You also quoted one solution, which you might recognize from some of your readings. Need more?
There are several more technically difficult methods which involve edits of dlist files or databases.
The folder arrangement of new backup versus old backup could also influence which way is best…
EDIT 3:
Continuing with the thought of “how different is the new layout?”, you’ll need to tell Duplicati where backup Source files are now. If you didn’t change anything, it would still expect to use drive letters.
This is a somewhat separate topic from what to do with the Destination side, but it’s necessary too.