Marina MacKechnie appears to have been the daughter of John Campbell MacKechnie, Chief Officer "S.S. Tung On" of the Hong Kong, Canton and Macao Steamboat Co.. See Hong Kong Daily Press 2 December 1940 here for details of the family.
During the Battle of Hong Kong, Marina Mackechnie was stationed at La Salle Relief Hospital. Her name/signature appears under "La Salle College" (La Salle Relief Hospital) on the left on the "Day Joyce Sheet" held by the Imperial War Museum.
See: https://www.iwm.org.uk/collections/item/object/30083388. An explanation of the "Day Joyce Sheet" is given at: https://gwulo.com/media/46458
Marina MacKechnie does not appear to have been interned at Stanley Camp.
Source
1. http://www.hongkongwardiary.com/searchgarrison/uniformedcivilians.html#_Toc43367292