Thank you Brian & Stephanie for your responses.
For Stephanie: Unfortunately, the Margaret you list is too young to match with my family (though I do believe the family may have lived in or around the Maughold area around 1847).

For Brian: This would seem to be a better fit. It would make Margaret only 15 (or thereabouts) at the time of her marriage and immigration. I will now order her death certificate here to try to establish a link.

I'm very new at researching my family and much appreciate your responses. If there is anything I can help you with in Australia, please let me know.