Yes, the Beryl Hunt entry is a mystery. Perhaps she was supposed to be Beryl Hunt Macalister? Or just an error in the entry at the time? They had another child in 1921, stillborn. I can't find any other children for them.
Frank Montagu Hillyard Gibson had a son, Eric Hugh Meredith Gibson born 1873 Western Cape, South Africa, died 1932 Maidstone, Victoria and a daughter Maude Isabelle Louisa Gibson born 1883 Richmond (mother Louisa Crole). She moved to New Zealand and married Alfred George Lucas on 6 April 1904. They lived in Wanganui and had four children.
I am hoping to find more information, through Gibson family members, on Claude Aislabe Vign Gibson (Frank's younger brother) and his first wife Edith Marion Clayton (married London 1881).
I have just found a Mrs C Macalister, 31, born Victoria travelling from Sydney to NZ in 1922 with Master B Macalister, 6. Record says that he was also born Victoria so am not sure if this is Constance, and her son's birthplace was incorrectly entered on the passenger record. It is conceivable, with a mother and father in Australia, that she might travel to visit them.