I believe that I have now established that two of William's & Mary's children married (on the island) as follows:

Ellen Gertrude Keig (although only named as Gertrude in the marriage record) married in November 1925 to Herbert Looney, a Farmer age 23.
Herbert's parents were Thomas & Marian Looney (nee Goode).

Irene Keig married in November 1933 to William Albert Moore, a Farm Labourer age 32.
William's parents were William Edwin & Anna Moore (nee Brew).

I have also discovered that William Keig married again (his second wife Mary Ann having died in March 1915) in December 1918 to Christian Garrett (nee Gill) a widow age 44.

As previously, can anyone please help with regard to Gertrude's and Irene's descendants?