Hello Ruth,
It's interesting to hear about your family's history in Fiji. I can certainly try to help you in your search for information on the missing son and any grandchildren.
Based on the information you provided, it seems that Arthur Alexander Addis had four sons who were known to be working for CSR at the time of his death in 1909. However, it's possible that there was a fifth son who was not mentioned in the newspaper report, so it would be worth searching for any additional records or family documents that may shed light on this.
Regarding the potential fifth son, F.M. Addis, it's possible that this could be a relative or family member, but without more information it's difficult to say for certain. If you have any additional details on this person or their connection to the family, it may be helpful in narrowing down the search.
As for any grandchildren born in Fiji, this may also require additional research and documentation. One possibility is to search birth and marriage records in Fiji to see if any descendants can be traced that way. It may also be helpful to reach out to any living relatives or family members who may have information or memories of their time in Fiji.
I hope this information is helpful, and wish you the best of luck in your search for more information on your family's history in Fiji.
Best regards
