Hi Deb, thanks for your email, good story for a detective i thought.

Answer to your questions
* Martha & Beatrice Ward, i did find living only at Calstock, Cornwall, in 1871 census (Martha was listed as married i think) if i recalled correctly...
* James's family; parents, brothers and sisters i discovered by accident in the 1871 census living at Bruce Mines, Algoma, Canada. I just googled John Ward miner census for memory! lol this is what appeared..
1871 census Algoma.bruce_mines Ontairo Canada
WARD John m 59 England Wesleyan Methodist English miner married
WARD {?} Mary f 55 England Wesleyan Methodist English:
WARD Joseph m 22 England Wesleyan Methodist English Mine labourer
WARD Keturah f 20 England Wesleyan Methodist English
WARD William m 16 England Wesleyan Methodist English
WARD Charles m 16 England Wesleyan Methodist English
Keturah Ward married Edward Kitto (Kitts) at Bruce Mines on 8 June 1872 there after have disappeared!
I also found by accident another brother of James 'Joseph Bennett Ward' buried c1902 at Nanaimo Cemetery, Nanaimo, B.C., Vancouver Island.
Sorry i have been unable to locate passengers list to either USA or NZ, i've also tried Ellis Island.
I think James went to the USA in search of Work!, as the Tin Mines were closing down at Calstock, Cornwall. The Ward family according to census were a mining family (later mining for Gold and Coal in NZ)
*Family story mentioned James actually went to San Franciso, and work on the blasting of Hell's Gate channel, (Main shipping channel) where he was injured by a stick of gelignite accidental going off, injuring his leg. Unsure when this was or what happened next. But the fact that he did come to NZ. also from the same story
another brother of James; 'Charles' lived at California (Goldfields), he was there at the time of the big earthqukae and massive city fire of California. .... been unable to find him.
* James arrived to Auckland? in c1874-5! and met a woman living in Thames, Coromandel 'Priscilla Higgins nee Moyle', who's husband had disappeared in the California Goldfields c1874. James and Priscilla had children out of wedlock
Mary Elizabeth Ward 1879
Charles Henry Ward 1880
James Ward 1882
Ernest Ward 1884
Priscilla Ward 1889
James moved from Thames in 1889 (as the Gold Mines were closing down), Work was hard to find in Auckland and not paying well either, so he found work with better wages and moved to the South Island, where he worked in a Coal Mine, known as The 'Dennsiton incline'. Once set up, he sent for his family and Priscilla to sell up and move down.
James and Priscilla were married at there home in Denniston, Westport on 14th July 1890, where it listed James as a Widower abt c1875
Iam not sure if James came by himself to NZ, but his parents did live and die in Thames, as well as 3 of his brothers found whom died at Thames &, Auckland as well.
James' son William John Ward died as a result of a mining accident, where a belt caught his leg and dragged him through the mine in 1917, where he died afterwards from sever injuries. William had a young family. An inquest was held, where it stated that he was a british subject born in New York c1874. I have engaged in a researcher looking for his birth certificate, but to no avail. James' daugher Beatrice Ward married George Kelly in 1895
* Yes Martha appears on William John Ward marriage and death certificate as his mother. Martha Ward nee Elston
* We have search electrols and NZdeaths, marriages, Wills for a Martha Ward - Elston etc, but turned up nothing. No Elston family came to NZ. There's been no Martha Ward / Elston whom married in England *free bdm
Well thats about all i have sorry. My best guess is that Martha gave birth to William John or another child! in New York and perhaps died there as a result from the birth or died on the way out to NZ. Im not sure if there are census or Electrols of New York for abt 1874-5
Cheers Murray