I found confirmation of the children from sources on familysearch, so I added them to the profiles of Robert and Jane.
So far the only child attached is Jane May (on WikiTree as May Jane).
For Margaret Brown Paisley, if she had children between 1915 and 1919, they should be easy to find. Any after the cutoff date for New Zealand's online BDM search will be more difficult.
If you haven't yet discovered Papers Past (aka the National Library of New Zealand), I recommend it. https://paperspast.natlib.govt.nz/newspapers
If you aren't yet a member here, I also recommend that you sign up. That way you'll be able toad your research.
If you are already a member, feel free to ask for help any time you get stuck.