Thank you so much X3non for your help thus far.
Unfortunately I am away for 10 days and cannot continue with this till I get back. I will then try the second approach first, and if it does not work, will try the first.
Some possible issues:
1. The file sizes may be different in the the Nougat firmware than specified in the Oreo scatter file. Can't check now. Will I need to amend the sizes appropriately?
2. Still not sure what dropdown option to use. What is actually the technical difference between the three options?
Lastly, for interest, where do you live? I'm interested in your time zone.