Hello Cousin to you too!
I am descended from William Neasmith and Margaret Murray's daughter Elizabeth who married David Matthews in Maneroo District NSW on 12 Mar 1850. Elizabeth and her widowed mother Margaret and siblings landed at Twofold Bay near Eden NSW in 1848 as part of Ben Boyd's Utopia experiment. They were seen as suitable people for his experiment in the colonies. The children worked on squatting runs in the area which I suspect Ben Boyd had set up. Margaret and Elizabeth married young men working in the area and when the gold rush started in Ballarat, they set out for the Ballarat goldfields, but that is another story. Mother Margaret, son William and Agnes all went to Sydney after the experiment failed.
No, I haven't found out who William Naismith Senior's parents are, but I suspect that your Charles Stewart Neasmith's name is the clue!!! He is the only one with a middle name!
Dijaks