Hello yet again Shona.
You may have heard it said that you can not be fluent in a second language, until you start thinking in that language, and I look upon research into our NZ pioneers in a similar light. Once you immerse yourself in knowledge of the period you are researching, things start to take shape, and help with your lateral thinking in the search for answers.
You say Sarah Vernon CAMPBELL was b. 1842; m. 1862; d. 1918 so she was in her 50’s before NZ started making progress to women's suffrage. If a woman of that period in NZ was married, she most likely was treated as a chattel, of her husband and very little by the way of assets / property would have been in her name to need, or be mentioned, in legal transactions, deeds. Leases etc. Those that were, were in the main wealthy spinsters or widowed.
When travelling, she and the pre-adult children would have been named on the husbands travelling papers, and they were modest affairs by today’s standards. While there were University degree courses that some women did; the guilds, Masons, etc, certifications in seafaring and steam power plants and steam powered transportation, the internal combustion engine was only just getting a footing [no drivers licence], so licensing was for more mundane things like around hotels / alcohol sales, food handling, and mining claims etc.
In the main women were in the home, nursing, and teaching, Communities were smaller and people had connections, so there was more chances of being known when it came to the likes of seeking jobs in the professions etc.
At the very top of this NZ board you will see advisory threads to assist you, and explain some of the best places to be looking for information in the locality of your search.
The reason for your specific reference to the National Library is not obvious to me, but feel free to ask. Try “Archway” and the on line pages of the leading regional libraries. Also the various Museums have a diverse selection of things old, even down to donated scrap books that happen to contain clippings from long defunct newspapers and periodicals.
All the best.
- Alan.