Thomas III Mattingly had a son by the name of Clement who was born in 1715, but by what everyone shows, he wasn't Walter's father, although he would have been old enough at 20 years old in 1735.
I really don't think Walter was from Thomas II's line, or his children by the research I've done, and others, on it.
One of the family got hold of a book once on our supposed Matney line, and it showed his great grandfather, Alexander Matney, being a Clements son, which was impossible for his age, and also it was proven that Alexander was the son of Walter Matney(2) (Not Walter Jr.). My great grandfather, Alexander Pate Matney, was named after this Alexander, which was his uncle, and Daniel Matney's (my GG Grandfathers) brother. The books were peddled over the phone back in the 1980's and may be where this came about.
There are three lines of Matney's in the Eastern Kentucky area as far as I'm aware, and those are from the two brothers, Alexander and Daniel Matney (Walter(2)'s sons), and the children of Brooks Matney, Walter(2)'s brother. They are the ones to settle the area, and the others were pretty much still in Virginia.
I don't know where Richard Mattingly's children went to, and if any are in Virginia, as he ended up moving while Walter stayed. I don't know where Richard ended up at after that either.