Donald was a shepherd, born 30 October 1799. I wonder how he came to meet Catherine, born in 1803 in Kingussie, 100 miles away. The family seem to have been in Archaracle after the marriage until about 1833, then moved north to the Badenoch region where Catherine came from. He then worked at Nuid More, a farm that had been run by McPhersons since the 1600s. It was managed by Capt Aeneas McPherson, a Peninsular War veteran invalided out after being wounded. I can only suppose he was somehow related to Catherine but I don't know how.
After Catherine's death about 1848 (I haven't found this anywhere), the captain emigrated to Victoria on the Indus, taking family and dependants with him. Donald was one of the dependants, along with some of his children. After their arrival, Donald continued working for the captain to repay his fare, before settling in Arthur's Creek and remarrying. I've seen a reference to Margaret Kerr also being related to the captain, but haven't been able to stand that up either.
The captain went on to New Zealand and died in Geraldine in 1875. NZ newspaper obituaries give quite a lot of detail about his life, but I just can't find any link to Catherine other than the surname.