Hi Susie,
I would lke that to be true, but after a trawl of the immigration records I cannot find them all arriving in the right time frame.
There are a GEORGE and ALEXANDER [brothers ] together on GOLCONDA in 1858.
But no viable James at all. And no William is placed well either.
A bit patchy and indefinite

IT is possible that others have
Resources to look beyond the State Archives for arrivals

Possibly one of these 2 under different spellings??
SNADDEN James 25 ship Alfred .1858 Moreton Bay. Reels 2138, 2477
SNEDDEN, James 24 ship St Helena 1854 Sydney and/or Newcastle and brothers Reel 2137, [4/4791]; Reel 2467, [4/4942]
Sue