[[ I am guessing the entry in the NZ BDM Births dated 1859 with the name NR (No Record) is most likely Miriam's birth record. ]]
The more time i spend looking through the NZ BDM the more i am finding how much is wrong on there.... guess that is what happens when you digitise the old records.
Not quite sure what you're meaning about ... "NZ BDM ... how much is wrong on there ..." ??
Question : What are you comparing NZ BDM's records with ... and what exactly is wrong
Remember that these are only Index listings which are viewable on the NZ BDM website (and from time to time spelling errors may crop up).

You need to purchase a record (* "printout" recommended) to get all the information available.
These are
official records - primary sources of BD&M information, in genealogy/family history - considered to be more accurate (and although not precluded from having an error, this is an uncommon occurrence).
[Some helpful info at this link >
https://www.thegenealogyassistant.com/index.php/store/three-brushes-with-death/43-news/blog-posts/314-what-are-primary-a-secondary-sources ]
[ * If purchasing records from NZ BDM, we recommend ordering the "printout" version - a copy of the register entry
(rather than certificates which have transcribed information).
~ Lu