Three possible marriages in NSW for a John YOUNG to a Mary J.
I don't have the arrival of any of the Young family.
The Sydney Morning Herald - Sat 20 May 1865 p.9
MARRIAGES
YOUNG - HENRY.-May 3rd, by special license, at St. Ann's, Ryde, by the Rev. G. E. Turner, George Edward, third son of Mr. James Young, of 12 Richmond-terrace, South Lambeth, London, S., to Annie, eldest daughter of Mr. James Henry, Ryde, Parramatta River, and granddaughter of the late Rev. W. Henry, of the London Missionary Society.