The family is in Hawkesbury, County of Prescott, Ontario in the 1851 Census.
Elizabeth Robinson, widow, mother in law, age 70, born Scotland
Donald McKilligan*, farmer, age 49, born Scotland
Margaret, age 47, born Scotland
James, farmer's son, age 19, born Canada West
William, farmer's son, age 14, born Canada West
Mary, spinster, age 17, born Canada West
Margaret, spinster, age 13, born Canada West
*that's how it is spelled on the census
The family of Benjamin McKilligan, age 54 is living beside Donald in the 1851, so perhaps a brother.
Karen