I found the website below tonight which gives the birthdate of Thomas Jefferson Vanderslice's brother Daniel Vanderslice as 10 Feb. 1799, which certainly fits better than 1779 with TJV's 1801 estimated birth. I notice that this gives the mother as Margaret "Cremmens" daughter of Abraham Cremmens. Gov. Pennypacker's manuscript states that Margaret 'Clemmons'was Daniel Vanderslice's(I) first wife (the names for the other two wives was not given). Daniel(II) was not one of the three children listed for Daniel and Margaret, but of the third, unnamed, wife. Still some sorting out to be done here.