Lawrence, I looked at the Braddan Parish Register image for the marriage of Frank Ridgway Harrison and Olive Christian Robinson/Cowin in order to find the name of Olive’s father. She stated that he was John Wilfred Cowin (deceased), rope-maker.
Then I found a tree on the Ancestry site which was compiled by a direct descendant of a sister of John Wilfred Cowin b 1893. There are several photos of John Wilfred Cowin’s brothers and sisters, Here’s the link:
But is there a question mark over whether John Wilfred Cowin was Olive’s biological father (since she was born the year before her mother’s marriage to JWC, and her birth is listed in the Manx Birth index under her mother’s maiden name, which presumably means that there was no father’s name on her birth certificate.
1918 Robinson Olive Christian Douglas A 2407
If JWC actually was Olive’s father, the Ancestry tree mentioned above also has photos of some of Olive’s first cousins.