Found a photo of a headstone in the Maughold Parish Church Cemetery that may help in answering some of the questions concerning Margaret and William Corlett. There are four names on this memorial marker.
Info on this headstone reads:
Margaret wife of William Corlett died Apr 26, 1894 age 73 (b. 1821) also [same headstone] William Corlett Died July 11, 1912 age 97 (b. 1815) also Jessie Looney Grand Child of the above died Jun 23, 1900 age 7 days also Stephen Looney who died Mar 31, 19?? photo cut off bottom of last two numbers, but it looks like 1922. Cannot see age of last child.