The Papakura District Council appear to hold cemetery records for that area ... but if not, they'll be able to point you in the right direction. You can find an email contact at the following link.
http://www.pdc.govt.nz
~ Lu
Yes they do and if you ask them, they might include the cemetery layout of Mary Ann's resting place.
The NZSG branch of Papakura, have transcriptions of the burials, this helps when headstones are hard to read, if you aren't in NZ and would like a photo of the headstone, let me know and I will take one, but won't be able to do it for a couple of weeks though.
Cheers
KHP
