All - you were correct. Once I installed the DMXZone Extension Manager, I was able to reinstall your extension plus DW fnally recognized the Database and Server Behaviors extension that I already had. I was able to salvage the page with my immediate concerns. Thanks to all of you for your offers of help. It looks like I'm going to have to go back to v. 6.
This is my second piece of mission-critical software that Adobe has messed up with its "updates." I also have used FrameMaker for years, and its 2015 release completely blew up the documents I was building. After many, many wasted hours spent on tech support with them, and after hearing them finally say "it's not a flaw, it's a feature," I had to go back to a previous version. They need a new set of developers over there.