This grave shows the resting place of Archibald Knox's parents, William and Ann, his younger brother Carmichael and his older sister Christina. It is not believed to have been designed by Archibald.
Carmichael was tragically drowned in Douglas Harbour in November 1893 at the age of 26. The link below will take you to the newspaper reports by the Isle of Man Times of Saturday 02 December 1893 (funeral) and also by Mona's Herald of 29 November 1893 (inquest and details)
https://www.imuseum.im/Olive/APA/IsleofMan/?action=search&text=carmichael#panel=search&search=0
William died in February 1901. He was born in Kilbirnie, Ayrshire in 1829 and came to the Island to work in 1856 at the sail factory in Tromode, and lived for several years in Cronkbourne Village, He later became a marine engineer and invented machinery for which he was awarded international certificates.
Ann was also Scottish and came with her husband to the Isle of Man in 1856. She was born on Lismore Island, Argyll in 1828.
Christina died in April 1931 and one of the silver communion pieces in St German's Cathedral was designed by Knox as a memorial to this sister.