Jesse, Sorry for taking so long to respond. I have a pretty good chart of the descendants of Thomas McKee (1695-1769). The one who married a Shawnee Indian woman. Unfortunately, I couldn't find a Rebecca Reagan, nor could I find anyone with 2 daughters named Sarah and Elizabeth.
The 1810 Census data that you found is interesting. There's a very high probability that the William McKee you found in Harrison County, Indiana is my direct ancestor and Thomas would have been his brother. Crawford County didn't exist until 1818 and was formed from Harrison and 2 other counties. William would have been 28 years old and Thomas 29. Also, Thomas McKee became a justice of the peace in Schuyler County, Illinois a few years later. William was married to Cassandra Frakes, sister of Thomas's wife, Hannah.
Here's a link you might find useful:http://www.dcn.davis.ca.us/go/getpizza/mckee/familynewsall.htmlhttp://www.dcn.davis.ca.us/go/getpizza/mckee/familynewsall.htmlThere's a link on this page that shows all of the McKees living in Indiana according to the 1820 and 1830 censuses in addition to some other interesting links regarding McKees. If you have a copy or transcription of that 1810 census, I'd sure appreciate it if you would send me a copy. Good luck in your search, Phil Jackson