Two of the many places that "Whistle, daughter, whistle" may be found are Sharp-Karpeles' 'English Folksongs of the Southern Appalachians', II, p. 169, and Vance Randolph's 'Ozark Folksongs', I, p. 411. I take back what I said about the song being derived from, 'The Maulster's Daughter of Marlborough', it's still possible, but there are enough differences to make it questionable.