Thank you very much Elton for an interesting and challenging posting.Here are a few comments that may only add to the mystery!
1.The father of John Randolph of Roanoke (1773-1833) was John Randolph (1742-1775) of Matoax (in Chesterfield Co.).The junior John Randolph was normally a stickler for genealogical matters, so I think it would be surprising if he had assigned the words "of Roanoke" to his dad.
2.The senior John Randolph and Frances Bland Randolph did indeed have children in addition to John of Roanoke.POCAHONTAS' DESCENDANTS (1985 edition, p. 126) lists three other kids: Richard of Bizarre (1770-1796); Theodorick (1771-1792); and Jane, for whom there are neither dates nor information about marital status given.
3.If the newspaper article you cited appeared in 1829, it would be interesting to know if it was using a contemporary quotation from John Randolph of Roanoke or something he wrote much earlier.If the former (and assuming the quote itself was accurate), it would suggest that sister Jane was still alive in 1829.
4.On the other hand, in his 1796 chart of Pocahontas' descendants, Benjamin Henry Latrobe says the following about the children of John Randolph and Frances Bland: "1. Richard Randolph of Bizarre . . . deceased.2.Theodoric deceased.3.John unmarried.Several others who died young."No mention of Jane, except perhaps indirectly as one of those who "died young," i.e., before 1796.
5.Unless, therefore, the 1829 article misquoted John Randolph of Roanoke or drew on something he said or wrote much earlier in his life -- before 1796 -- it would appear to be introducing something "new" -- unless, of course, my own knowledge of what's already out there about this family is lacking: a distinct possibility!
Thanks again for posting the quotation.Would welcome your reaction to the above.Fred