As I recall from the time the song first became popular, 'Old Francie' himself claimed more to have remade it from an older song (The Braes of Balquidder, or some interim song?) than created it holus bolus. For intermediary songs, e.g in 1924 Sam Hendry collected The Flower of Glenleary, which uses the Balquidder tune and some vaguely familiar line construction. As for the family now making larger claims than the originator himself did - what's new? Families (nearly) always do that.