The Robertson book is peculiar. For each person it gives the number of boys and girls they had. Then on a later page it lists the names of those who went on to become parents. David Meade Randolph is supposed to have had 6 boys and 2 girls, but only William B is shown as a parent, so the others aren't named.
Richard Randolph the antiquary is believed to be one of them, but I don't know who believes it or why.
I suspect the Robertson book was all compiled by writing letters, not from official records.
I haven't seen the Stuart Brown books, so I don't know how much they add, apart from continuing to later generations.