Hello EilHolli
You may already have these, but in the South Australian Register (Adelaide) 20 Aug 1859
DIED - Drowned from the wreck of the Admella Steamer, off Cape Northumberland, on or about the 6th of August, Thomas Rolfe Mensforth, aged 26, eldest son of the late Mr John Mensforth of Adelaide. Deeply regretted by all who knew him.
1 July 1882 - Deaths
IVERSON - on 25 June, Mellors Rd, Glanville, Charlotte Cecelia Iverson, wife of Captain N H Iverson, and youngest daughter of the late John Mensforth, 51st King's Own Light Infantry, Manchester, England
There is a piece in Feb 1861 reporting on the suicide of an Ann Mensforth, and it mentions her mother Elizabeth??
I'm sorry, none of this helps with your original query re Edward's birth.
Dazey