McMahon family

I've already posted a wee bit on my Great x 3 Grandparents, Ellen Tobin and Michael McMahon.  See here. 

I've since found out a bit more about Michael McMahon.

In 1862, Michael McMahon, of Gabriel's Gully, was registered as a claimant to a mining right as of 13 September 1861 at Tuapeka.

Following his marriage to Ellen Tobin on 7 April 1863, I'm now certain that they had at least three children (probably more).  They certainly had:

1. Margaret McMahon (1867) - my great great grandmother.

2. Michael McMahon (1869)

3. Thomas McMahon (1874 - 28 June 1911) married Mary Amelia O'Flaherty (1880 - 12 September 1916, Wellington).  Thomas worked as a clerk. Sadly neither Thomas or Mary were to live long lives, with Thomas dying prematurely at the age of 37, just a month after the death of their four year old son, and Mary dying five years later at the age of 36.  Both parents and son are buried together in the Catholic section of the Karori Cemetery.  The sole survivor of the family would appear to be their daughter, but I'm unsure whatever became of her. Perhaps someone can assist?  I do know that Thomas and Mary had two children:
   3.1 Thomas Michael McMahon (1907 - 24 May 1911)
   3.2 Mary Elizabeth McMahon (1910)

By 1870/71 Michael Snr was listed as living at the "public house and dwelling house" in Welshman's Terrace, Brighton, in the Buller District.  Clearly, looking at the electoral roll, many of the local miners lived there.  Quite possibly, as was common, Ellen and the children lived elsewhere - Dunedin possibly?