Question: 
I was left a heap of papers by my father, its all laid out who ancestors were, however I can only supply outside proof for official certification via birth certificate linkages back to my father and his
father. I'm not sure how to get these certified.

Answer: 
Predecessor estates were created as public records.  How those records were succeeded here in New Zealand as far as Tangata Whenua were concerned was by all intent and purposes administered through the Maori Land Court.  Generally the rangatira of the haapu (sub tribe) prior to the issue of titles were assigned the task of identifying various names who had rights to various lands around the motu/islands.   These were recorded in minute books.  If tupuna succession are found in the minute books the relevant page can be certified by Archives New Zealand, Auckland. We've gone there after finding the relevant minute book page and have given staff the reference to certify.

There is a website where you can search a NAME of a predecessor in the Maori Land Court minute books.  The Auckland University Library hold all the Maori Land Court minute books for all New Zealand 

Here is a link to the Maori Land Court Minute Book Index

When the births, deaths and marriages Act came into being around 1911 for tangata whenua we were then able (sometimes) to use these records to trace ancestry.

I know this can be challenging for many who cannot find these connections.  At best we can only register our individual crown lands until such time we are able to have access to resources to assist.  

Administrators need to be found for each predecessor estate and so certification is essential for this process. After that it may rely on family authentication.  But don't quote me on this as this is only a suggestion and I cannot say what the successors of a predecessor's estate may want to do.

Here are some other ancestry search links

Family Search

Find My Past