Thanks for the replies!
Steve, 90% of what you said is over my head, so I won't be attempting what you're describing. But I sincerely appreciate you trying to share knowledge.
Klojum, I think what you're saying makes sense and it will be a very simple solution, so I'm going to go that route. Maybe I'll try to just create the disk image like you said, but then I didn't have any issue with the NOOBS process--everything was working fine until I formatted the other partition and added the files to it.
Thanks again to you both.