Donna, for this time and place, you need to separate fact from fiction.
First:What is the source of the information that a John McKie and Esther Hawthorne were the parents of David McKee (d. 1795)?Unless you can point otherwise, it appears to me to be an overeager person who tacked on a name in submitting a genealogy to the Utah Family History Society.With the spread of the internet, it didn't take long for this to be accepted as fact.
So let's look at it further.The IGI says that John McKie was of Minnigaff, in Wigtownshire, in southwestern Scotland.It is well established that the Minnigaff area was the home of the McKie family.See Williams Scot, ed., Parish Lists of Wigtownshire and Minnigaff, 1684, Scottish Record Society 72 (Edinburgh:for the Society by J. Skinner & Co., 1916).This lists many McKies living in that area at that time.
This 1684 list shows that there were 246 heads of households in Wigtownshire named McKie, with the highest proportions in Minnigaff, Penninghame, Wigtown, Glasserton, and others.The surviving parish registers for Minnigaff begin in 1694; for Penninghame in 1695.But the problem is that, because most of the people in this area were Covenanters (during the "killing times" of the 1680s), many had already left for Ireland before the parish registers begin.
The earliest account of David McKee's family (in Durant's History of Allegheny County, Pennsylvania, published in 1876) mentions some things that indicate that he was part of this southwestern Scotland "clan."He was "by tradition" "baron of Learg."The chief of the family was the laird of Larg, whose estates were forfeited as a result of the conflict during the "killing times" of 1685-1688.This would indicate some sort of relationship, but probably not a literal descent.
The other point to your question is which McKees were in fact associated with David's family.His children are known.His son Thomas died unmarried before 19 Feb. 1779, so he had no family.The son James is the most mysterious.He was alive in 1794 in Versailles Township.
His son Robert died before 5 Apr. 1782 in what was then Westmoreland Co., PA.Letters of administration were granted to his widow Susannah.Children were Elizabeth (m. Samuel Sinclair), David, Robert, and Mary (m. Hugh Torrance).I haven't identified David and Robert.
Son David died Sept. 1785 in what was then Washington Co.He had Sarah (m. THomas Whigham), Mary (m. ---- Patterson), John (1782-1846), James, and David (d. 1853, age 66).
The name "McKee," you have to remember, is pretty common, especially in areas like the Pittsburgh area with many immigrants from northern Ireland (who in turn were descended by people who came from southwestern Scotland).Just because they lived in the same region doesn't make them related.
As of the early 1780s, the only other McKees which lived near David McKee were:
Gavin (Guian) McKee (1751-1827), who in 1789 sold a tract of land in Allegheny County to John McKee, founder of McKeesport, and went to Fleming Co., KY
Robert McKee (d. 1828), married Elizabeth Miller, remained in St. Clair Twp., Allegheny Co., PA.Had son Guyon; wife's brothers John and William applied with Gavin in 1820 for a Revolutionary War pension; so Robert was probably Gavin's brother
William McKee (d. 1823), married Margaret, possibly David McKee's daughter Margaret (his will mentions his daughter Margaret McKee).
These three were in the vicinity of McKeesport by 1775.I'm from Gavin; the oral tradition in my branch says that the McKeesport McKees were relatives.Most likely, though there is no evidence, Gavin, Robert, and William were brothers and they were nephews of David.Tax lists from the 1780s show them living next to each other.
Andrew McKee (b. 1747) of Beaver Co. may have been related, but he immigrated later.
There are some other unlinked McKees in Kentucky and Ohio who seem to have similar traditions of origin. The Rockbridge County, Virginia, McKees seem to have a tradition that links them to the McKeesport family.
However, I would be dubious about connecting others, like Alexander McKee, etc.You have to remember that the name was common.Unless you can demonstrate some link (like a deed or possibly an oral tradition), I wouldn't tie them together.