When Alexander McKee (b. 1778) had his children, he had four boys and two girls that I know of. I'm sure that there were other children that either stayed in Ireland or England (no lead on any) or did not live to adulthood (more likely). With four boys, one would imagine that Alexander could be sure that the McKee name would be carried forward by all four of his sons. The reality has been quite different.
Joseph McKee (b. 1804) had three sons. His son Joseph (b.1843) died before he had issue. George (b. 1839) had one son who never married or had no children that I know of. Only Joseph's youngest son, Robert (b. 1853) had sons. This line of McKees have carried the name into the present.
William McKee (b. 1812) had one son, William (b. 1853). He died unmarried and without issue that I know of.
Robert McKee (b.1816) had no sons.
Alexander McKee (b. 1827) had three sons, all of whom had families that included boys, who in turn married and had sons of their own. This line of McKees have carried the name into the present.
Therefore, anyone who is looking for the contemporary bears of the McKee name from this family need to look at descendants in two lines:
--Joseph's youngest son, Robert
The interesting part is that the producer of the most descendants in this family is the daughter of Joseph McKee, Mary Jane (McKee) Booth (b. l838). Mary Jane had ten children, who each in turn married and had many children of their own. When chasing information on this family, I spend fully half of my time chasing information on a Booth descendant.