Yay... I was successful in transferring all of iDVD, including all seven theme folders (for 7.0, 6.0, 5.0 and Old). I used my 4GB thumb drive. I made sure the location on the MacBook was exactly where my iMac has the app and the correct folders with all seven themes folders.
So, this is where everything is stored and it works perfectly:
~ iDVD app (with the icon) - stored in Mac HD, Applications.
~ iDVD folder, which includes the 7 Themes folders - stored in Mac HD, Library, Application Support
Fyi... I also deleted that other secondary location on my iMac that I somehow had a "duplicate" iDVD folder which was not read by my system. Now, both my iMac and MacBook have the same folders in the same place and iDVD pulls up great. Of course, it will mostly burn properly in the MacBook because of the earlier OS in it. I could not get my long movie to burn on my iMac using Sierra after many attempts. I had chapter markers in it that I created using MetaDoctor (easy program for $5). However, when I Airdropped the archived iDVD movie to the MacBook, it burned without any problem to a dvd using my Apple Superdrive. My movie even had the chapter markers (scene selections) with the MetaDoctor program and there was no problem. I didn't even have to use the older iMovie for the chapter markers.
So, it was great that I was able to:
create my 1hr 50m movie in the latest iMovie on my iMac,
save it to a file,
open it in QuickTime,
convert it to a .mov file,
import it to MetaDoctor program,
easily add my 14 chapter markers in it,
save it,
then drag it to my iDVD project (while still on my iMac with Sierra) which created the scene selections instantly.
My iDVD theme was Confetti.
I also had another 1m 35s mini loop video on the main menu page, and a photo in the display box in the other three menu pages.
When that was done, I selected to archive (File... Archive Project) the iDVD project so it can keep all its media used in it together wherever it is saved to. Then I dragged the archived project in AirDrop to the MacBook.
After it downloaded there, I opened up the movie file I sent, which automatically opened the iDVD on her MacBook that I had installed there.
In iDVD I selected Professional Quality and Maximum burn.
All I did next was clicked to burn, and put in a dvd in the superdrive I connected to it. Done, 3 hrs later. No issues because the MacBook has Yosemite.
