The siblings of William Austin in his profile are all listed as being born in Little Shelford, Cambridgeshire with the parish register recording all as the children of James Austin & Elizabeth. Indeed there is another child, William Austin baptised 20 August 1820, Little Shelford the son of James & Elizabeth.
Census records however reveal that the William Austin whose marriages are included in this profile (Austin-4153) was born in Hawkshead or Cantebury Kent. Unfortunately no parish record I caan trace reveals his parents. His siblings you record, I am afraid are incorrect.