I think Jean Morris was Anna Philomena Morgan based on some tiny things, like the fact that she used to say her husband was Mick (Michael) Guidice and her name was Jeanette Guidice.
Jeanette is the same alias of her mother Jeanette Constance Routledge, whose real name was Johanna Marthina Brits, daughter of Adriaan Brits and Anna Grobbelaar.
Her wealthy mother, who was the reason Jeanette Constance was so eager to have a death certificate for her daughter, was Anna Aletta Susanna Grobbelaar, who married at least 4 times, one in NSW and 3 in South Africa.
Anna married Adriaan Brits in Boshof, South Africa on 18 January 1892. Johanna was born on 7 Feb 1893. I haven't found a death record for Adriaan yet.
In 1908 Anna met John James Morgan in South Africa. They married in 1909 in NSW after they returned from South Africa. She gave the maiden name Alice Hannah Morgan on her marriage certificate (maybe Adriaan was still alive?) and later on (1911) her granddaughter Anna Philomena was registered Morgan although she wasn't related to John James.
John James said during the police inquiry that he sent money for Anna's children to be brought to Australia (one daughter and two sons). One of the sons was Johannes Nicolaas. I haven't been able to find the other one yet. The newspapers wrote her name Anna Britzz.
He also said that Jeanette Constance's real name was Johanna and that she was with a man (Sidney George Tiplady) around the time she got pregnant, and that her daughter born in 1911 lived with him (John James) and Anna on and off for some time.
Johanna registered her daughter Anna Philomena Morgan and the name she gave on the birth certificate was Jeanette Morgan. During the Pyjama Girl inquiry she said her mother Anna registered Anna Philomena.
John James started divorce proceedings against Alice Hannah Morgan (aka Anna) in 1920 (decree absolute in 1922) on grounds of desertion. Apparently she had returned to South Africa. He married again and died in 1945 soon after the reopening of the Pyjama Girl inquiry.
Anna/Alice married another NSW man in 'Community of Property' in South Africa, Seargent Colin Jones of Mudgee. He died in 1927 in South Africa and she married John Pressley in Hamburg, Germany according to her death certificate.
John Pressley died on 22-23 August 1943 under suspicious circumstances ("death from fractured skull caused in an assault by some person not yet found"). The Australian newspapers referred to Anna as Mrs. Prestley.
Alice Pressley died on 31 August 1949 in Boksburg, South Africa and left a considerable sum of money, around £2000, to her granddaughter Anna Philomena. The money was split between Jeanette's two sons and one daughter. (Jeanette died on 20 June 1947).
She had used the maiden names Porcheron and Owen on her marriages in South Africa as can be seen on her death and probate certificates available on FamilySearch.
I think this story could be one hell of a film!