Lots of gratitude to Library Addict, Apesmom, and Blossom for all the plug-in tips.
I spent last evening happily splitting my bundles into individual books. Love all the new cover plug-ins. I still enjoy manual cover searches on special books, often public domain where I want the 1st edition dust jacket or pulp pb cover. Some of my best have come from eBay. The Modify Epub plug-in allowed me to go back and replace covers with the ones that I already found for the Calibre display.