If Malinda was John and Mary's daughter, the Madison and Malinda would have been first cousins. Not an uncommon thing for them to marry under the circumstances.
If you find anything about the Schroeders, especially if you find they came to KY, I'd love to know about it.
To answer your question about relation to the Runners: Yes, I believe I am; I believe the Renners of Rockcastle County, KY, and the Runners of Warren County, KY, are descended from brothers--Adam and Jacob, sons of Adam Sr from Montgomery/Wythe County, VA.
There is a reasonable amount of circumstantial evidence that points that way. The name difference is no big thing: the Warren County Runners are called "Renner" in the earliest record I know of; our Jacob Renner is called "Runner" in the earliest record here; our family was called Runner as often as Renner for a couple of decades in KY; even old Adam Sr was Renner and Runner in VA.