Hi Jess
You will probably receive better assistance with your search if you post to the RootsChat Canada board .
Do please however mention, or provide actual links, to your New Zealand board threads for this family.
Just noting from the Obituary of Archibald STEWART (1815-1895) [see the link given at Reply # 5] ..."At the age of eleven years, he (Archibald) went with his parents to Nova Scotia.."
As you now know that Euphemia McLEOD married Choan STEWART in Canada (Breton), it seems logical that Canada is where Choan's first wife, Anna died.
~ Lu