Eric,
Finally had time to try that. Sorry to say, it is now a total disaster. All Safari Bookmarks are virtually unrecognizable on both devices. There are only about two remaining folders and then a slew of mixed bookmarks in the side bar. Favorites are virtually decimated. Having deleted the bookmarks on the old iMac, I expected the new one to be unchanged and the old one to reflect the new one. They are the same - just totally screwed up and with maybe 80 or 90% missing, or so it appears.
Now, on the old one, I exported the Safari bookmarks onto my desktop in case of problems, but I did not do the same on the new one, thinking that that one would just set things straight.
I need to fix this NOW. Is there a Safari bookmarks P-list or something I can access in this new one to restore things for now?
Right now, I will try to reimport the folder I have on the old iMac desktop to get the old one back in shape, but I really need all the bookmarks and, for example, updated passwords of this one. (Come to think of it, this one remembered THIS password.)
(One reason I have not been synching Safari on iCloud is because of strange experiences ten years back.)