This is fascinating stuff - and essential to our understanding of the oral tradition as a whole really, which depends upon songs being passed around and remade by other singers. One wonders to what extent these re-makings were regarded as the intellectual property of any given singer, and whether or not this contributed to further remakings of the song to distinguish it further, or even if this was expected. Whatever the case, something must have given rise to the innumerable variations of Barbara Allen. We still talk of making a song our own, and do so with considerable pride even if we don't stray too far from the collected form of the song, but even so in looking at collected forms we coe across intriguing variations. One such is Mrs Pearl Brewer of Arkensas whom Max Hunter twice recorded singing All Down By the Greenwood Side (a consummate reduction to the pure essence of Child #20 with a melody to chill you to the marrow) but on both occasions she sang it quite differently. One wonders how differently she sang it on other occasions. I've come across other examples of this fluidity in traditional singers, and would be interested in a broader exposition on how traditional singers varied their songs from one performance to another, especially in the light of making a song their own. On one occasion Jim mentioned a singer extemporising certain verses, which ties in with other traditions I've come across - be it Yorkshire fishermen, Welsh guisers, Serbian gusle players, Indian village musicians insulting guests at a wedding, or Davie Stewart's additional verses to McGinty's Meal an Ale. So - food for thought & further crack I should think...