Dispute was possibly over Religion:
William was baptized and married in the Catholic Church as was his parents.
While in Waimangaroa Margaret Lapsed and the children did not attend church.
Samuel was baptized in the Anglican church
Margaret is listed at death as Presbyterian.
This is an interesting speculation .
However I think it a little strange that a strict Catholic, wishing a strong Catholic upbringing for his children, would be deserting his marriage. There had been ample time to sort these religious differences over the years of the union.
Perhaps you can tell us, why did Margaret remain in Australia until 1902?
Was there someone contributing for all those years to her support and that of her many children?
Was the man she later married originally from NZ?
Sue