Cromarty on Family Tree Circles

Both came from Ross and Cromarty in Scotland. ALEXANDER was born in Cromarty in 1814, to William HOlM and Margaret WILLIAMSON. Isabella was born to Alexander MCALLAN in Logie Easter in 1818. Alexander was a sailor and arrived in Australia in 1858. He sponsored his wife and son Alexander and they arrived in Sydney in 1865. Young Alexander ended up in Tenterfield, but I do not know what happened to his parents. Family lore has it that Alexander was drowned in Brisbane Waters, but I can find no proof of this, and no record for a death of Isabella. Any suggestions would be greatly appreciated.