I can't find a marriage for Louisa & Robert in the online QLD BDM but that might just mean it was spelt incorrectly not that they didn't marry?
Below is a link to a story in Trove from 1948 showing that Jean Hubbard married Neville Parsons of Atherton.http://trove.nla.gov.au/ndp/del/article/42607514?searchTerm=...
The below gives great detail about the wedding, it even has a photo. It also lists the brides sister as Mrs G Howell.http://trove.nla.gov.au/ndp/del/article/42609202?searchTerm=...
The 1954 electoral roll shows Robert Hubbard Snr living at Kairi with his wife Louisa (his occupation is listed as Carpenter) & also Robert Hubbard Jnr & his wife Jacobine Eunice are living at Kairi (Robert Jnr's occupation is also Carpenter)
Jean & Neville Edward Parsons are living in Atherton in the 1954 electoral roll, his occupation is garage hand.
There is also a Herbert Geoffrey & Phyllis Millicent Howell living in Kairi in 1954, his occupation is farm hand.
The 1980 electoral roll shows Herbert & Phyllis as managers of the Herberton Caravan Park along with son Colin Graham & his wife Beverly Elizabeth Howell - Colin & Beverly are in the current phone book living at Mission River in Qld.
Maybe you could contact the & ask about photos?