There seem to be maybe more records on the Qld BDMs relating to the family.
Births to George and Harriet seem to include a daughter
Pierpoint Joseph George Harriet Louis 16 mar 1870 1870/001262
Pierpoint Harriet George Harriet Lewis 01 Nov 1872 1873/003187
Pierpoint Louis George George Harriet Lewis 31 Aug 1875 1875/003744
Pierpoint John Thomas George Harriet Lewis 31 Aug 1875 1875/003745
Marriage of Samuel (no guarantee without certificate)
Pierpoint Samuel Hooton Emma 29 Dec 1881 1881/001125
Children of Samuel to 1889
Pierpoint Henry Joseph George Samuel Emma Hooton 12 Dec 1882 1882/006297
Died 19 May 1883.
Pierppint Samuel James Samuel Emma Hooton 25 Jun 1884 1884/ 007714
Pierpoint Maud Adeline Samuel Emma Hooton 30 May 1886 1886/009083
There are also marriages of a James and John in 1880s - wonder if cousin James travelled with the family?
One of the children of this James is Harriet Lewis Pierpoint - seems this would HAVE to be a relative.
Couple of deaths as well
Hariott Pierpoint Parents Joseph Lewis Mary Low 29 May 1907 1907/003560
Samuel Pierpoint parents George Pierpoint Harriet Lewis 22 Apr 1912 1912/004405
They should all be online
https://www.bdm.qld.gov.au/IndexSearch/BirIndexQry.m with others that may also be family members
There are more marriages before 1914 which may also be your folks. Would be worth checking all the Pierpoints online & putting them into family groups.
Marriage of a Joseph 22 Dec 1903 & Harriet 8 Jul 1891 - I don't see the twins?
You may find some grandsons of George and Harriet serving in WW1 & the next generation in WWII
www.naa.gov.au - record search - search as a guest
Trish