Hi James,
Re... "His wife (Cecilia Webster) came from a whaling family, based in Sydney, but her father died when she was about 5. Her mother remarried a year later, but I don't know what Cecilia would have been doing in Twofold bay when she got married at age 17.
It's all a bit of a mystery. "
Google: twofold bay whaling
Twofold Bay (Eden), was the "whaling capital" of New South Wales!
Maybe, her step-father was in the whaling game?
Maybe, her mother resided there, with her second husband?
You said the death certificate has "30 years in Victoria". Is there any mention of time spent in NSW?
Mary