I'm not sure if there is a connection but the Bradbury/Coverdale marriage happened in Tasmania Australia.There were 4 sons of that union, two of whom married and only 1 had descendants apparently. The only surving descendant that I know of is female and lives in New Zealand. It is interesting though that your ancestors have the same names! I think there is a lot more research to be done! Bye the way there seems to be a ton of John Coverdale's and it was a popular name in my family line way back then.