I saw your post and think that your Donald Matheson is the one I am looking for. I am descendant from an Euphemia (Effy) Matheson. Listed on her grave are her parents Donald Matheson and Mary Cameron. Effy was born abt1834 which would make Donald 18ish when she was born. This could fit if he had children before he migrated. Effy's children are born in Australia, I am yet to find any information about when she immigrated here.
Please contact me about whether you think this is the right Donald. I am currently at a dead end.