BISA [Biographical Index SA] does not mention George and Sarah YOUNG. I have been through all the passenger lists to 1851 and did see that couple with one child plus a number of George YOUNGs on their own. There are no births recorded on the CD for children to George and a mother named Sarah.
The YOUNG family who arrived on the "Katherine Stewart Forbes" I have eliminated since it appears they came from Scotland.BISA (though not always accurate) has the following:- YOUNG George d: by 1846 arr: 1839 KATHERINE STEWART FORBES occ: Labourer m: Cath nee HILL-RENNIE par: Archibald and Isabel nee MORTIMER b: 30.3.1796 Ballaleisk CLK SCT d: 22.12.1871 ch: Geo (c1818-1876), Isabella PRICE (1823-1873), Mgt, Chas Jas, Kath, John, Anne
Unfortunately there were five recorded George YOUNGs, of a similar age, i.e. born between 1812 and 1819 whose death records do not name a relative.
Did the parents and/or siblings of John also move to VIC?