Thomas Bennett McBeth/MacBeth and Elizabeth Catherine Mary Mason are my branch (well, my husband's branch, anyway), so I thought I might weigh in and add what I know.
This couple were both living in NZ by 1872, in time for the birth of their daughter Eliza Charlotte (my husband's gr. grandmother). She was born on 11th December 1872, in Cashel Street East, Christchurch (registered in Jan 1873) - I have a copy of the entry to prove it!. Her father's profession is listed as a Plasterer, and her mother is listed as Elizabeth MacBeth, formerly Mason, so they were doing the common law thing well by 1872 as well.
I was not able to find their marriage cert, because I was looking in the wrong period (1868 to 1872), assuming, of course, that they were legally married before producing offspring, and that all the details attached to all Birth/Death certificates I have concerning this couple were correct (age when married - 22 for Thomas and 21 for Elizabeth, according to their Death Certs). Hmm, next time, I'll be Devil's advocate and widen my search.
The MacBeth family, complete with sons Thomas and Robert, had moved to NSW by 1883, as Thomas senior to appears in the Sands Business Directory for that year, as a Plasterer. He also appears in 1887, and Elizabeth has entries for 1887 and 1888, as a midwife. They move to Victoria by April 1892, as they are resident in the town of Warracknabeal, in time for daughter Eliza Charlotte's marriage to William Alexander Patterson. Elizabeth was practicing as a midwife at the time, including the birth of eldest granddaughter Jessie Lillian Patterson in the June of 1892 (married just in time!). By 1898, they are back in Sydney and both listed in the Sands directory for that year.
Interestingly enough, Eliza Charlotte returned home in 1904 for the birth of her youngest son, Sydney, which unfortunately did not go well - she died at her parent's house, at 341 Cleveland Street, Redfern, on 16 August 1904, the day after he was born. Maybe it was a troublesome pregnancy, hence the return home? She was buried in Rookwood Cemetery, Sydney, leaving husband William to bring up their six young children alone, back in Warracknabeal.
Thomas and Elizabeth also had an adopted daughter, Pearl, who married James Henry Brooks in 1906 in Windsor, NSW. Not sure if she was adopted in NZ or NSW, however.
How's that for some further info on this couple?!?
Regards
Jenny