Ten years late! Here is the part of the story I have pieced together.
John Plummer ROARK and Frances Emily BOLTON are my grandmother Hilda Frances' grandparents. I believe they both died young, in mid and late 1870, and that alcohol may have played a part (Newspaper Archives). The children you have listed here match my Victorian BDM research (AUS).
John Allen ROARK, Hilda's father, married Jane Ann DEUCHAR: Edward Bolton ROARK married Diana Clarke DEUCHAR.
John became a wealthy man as a stockbroker and shareholder. He and his family lived in Elsternwick and then Toorak.
Hilda married James Albert (Bertie) ANDERSON of Prahran who distinguished himself in the 5th Battalion (Gallipoli and Western Front)during WWI and later inherited then developed Anderson's Furniture, the family business, with Roy ANDERSON his brother. Some of John ROARK's estate passed to Hilda and Bertie. Unfortunately for me, the wealth subsequently dissipated in my mother's family line after her early death ;) -- but wealth's not all that counts!
Hope this is of interest and use. I can give more details on request.
I would love to know more about Alicia Eleanor.
Did she ever talk about the little twin girls or her parents?