Amanda I will email you.
I found listed in Monumental Inscriptions at Bunnerong (the headstones etc were moved here after the Elizabeth & Devonshire Street Cemeteries were cleared.) Grave No. 1409: William Denis and Jeremiah Joseph McCROHON the sons of Quarter Master Serg't John & Emily McCROHON of the 4th or Kings Own Reg't, the former died 18th February 1834 aged 4 years and 10 months, and the latter died 15th June 1834 aged 4 years and 5 days. In 1969 the Headstone was Upright and the Condition Good.
So William was born April 1829 and Jeremiah born June 1830, what a tragedy.