Going on the idea that it might be useful to trace Edith's travels across the Atlantic for clues I found some interesting things which I'm posting in chronological order to clarify a few things.
8 Oct.1913 married Henry Edward Porter in Toronto
16 Mar.1914 son Henry Edward Porter born Toronto (born 5 months after parents' marriage)
31 Oct.1914 "Missanabie" arrived Liverpool, England from Montreal (was Edith in Ireland from Oct.14-Dec.15?)
Edith F. Porter, 21, Henry Porter 7 months- 24 Addison Rd. Dublin
11 Dec.1915 "Missanabie" arrived St. John, N.B. from Liverpool, England (Edith must have been pregnant by now)
Edith F. Porter 22 married res. Toronto 3 yrs; Henry Ed Porter 2 born Toronto
9 Apr.1916 "Sicilian" arrived Liverpool, England from St. John, N.B. (Edith coming to have baby in Dublin)
Edith Porter 23, 11 Seville Place Dublin
12 May 1916 daughter Edith Porter born Dublin
and if this information is correct-
13 Mar.1918 daughter Florence Porter born Canada