Well, these are your relatives, so I'm just trying to understand / help.
In 1840 we find in the US Census eight McKee heads of household in Ripley County.
Five McKees are recorded in Jackson Township: David (60-70), Edman (20-30) (thus -- not indexed by Ancestry for some reason but next to David), Joseph (20-30) (same page as David and "Edman"), George R. (30-40) and James (40-50) (the latter two on the same page, indexed in "Johnson" Township although the Ancetry image header says "Jackson.")
Samuel (30-40) is in Delaware Township. The two others are indexed in Otter River Township: Eli (20-30) and Thomas (20-30).The two in Otter River are also near neighbors.
David and his first five sons per your first note in this query are here: Samuel, Thomas, Eli, Edmund (Edman) and Joseph. A little puzzle: you suggest that Eli and Edmund were deceased by 1840.A 15-20 year old son and 15-20 year old daughter in David's household (Simon and Rebecca) round out the family. David's age matches your data, born between 1770-1780.
The other two, George R. (for Riley) and James match well as the sibling sons of James McKee born abt. 1760 in my earlier note.The fact that they are living in such close proximity to your David could be mere coincidence. Or there could be some kinship.There were three more McKees in nearby Dearborn County, another James, a Daniel and a John.Tough to say whose who.
I'm also puzzled as to why I can't find David in the 1850 or 1860 full-name index Census records, since he died in 1865. Would be nice to corroborate his place of birth ...