I had a peek at this. If you go to http://wc.rootsweb.ancestry.com/http://wc.rootsweb.ancestry.com/ and search for the names, you will find it there.It is something concocted by an LDS member for the Ancestry File, since 1991.There are some serious problems with it.
First, the compiler evidently is descended from Thomas McKee, who died in 1814 in Butler County, PA.He has this Thomas being the son of David McKee, which is impossible, since land records prove that David's son Thomas died unmarried.
Second, the list of David's children is incomplete.
Third, according to the IGI, which must have used the original register as a source, the David baptized in 1706 at Drumbo, Down, was the son of a Thomas McKee.There is, of course, no way to know whether this is the same one who died in 1795 in Pennsylvania.
I'm not sure of the origin of "William McKee" and "Marjory Stewart," nor of "Prudy McCleary."Marjory Stewart appears as the name of the wife of John McKee and as the parent of Robert McKee (d. 1766 Rockbridge Co., VA) and grandparent of Alexander McKee (d. 1822 Maury Co., TN) in a post to McKee-L in 2000 (see http://newsarch.rootsweb.com/th/read/MCKEE/2000-08/09674295100)http://newsarch.rootsweb.com/th/read/MCKEE/2000-08/09674295100).This again looks like a "concoction."It could be that someone along the way changed the name "John McKee" to "William McKee."
The documentation for 18th-century Ireland is poor.Most Presbyterian registers don't survive for the period, and wills were burned in 1921. Newspapers started later.There may be papers of landed families that survive, but information in them would be limited----things like payments of rents, leases, etc.So if we are to have any realistic genealogy for the earlier generations of David's family, it would most likely come from a long lost 19th-century traditional genealogy that has sat somewhere forgotten.But this seems unlikely, since the author of the Allegheny County history (1880s) seems to have included the traditions he could find.DNA holds promise for at least linking the different branches.