On the Lönnrot poems about Kullervo: I've read they were based on three or four separate elements that were combined into one; a poem about the Son of Kaleva/Kalervo, a slave who works as a shepherd and takes his revenge on his mistress after his knife is broken, a poem about Turikkainen or Tuiretuinen or Turo, who seduces his sister and unknowingly causes her death; and a poem about a man who goes off to war and asks his family if they'll cry for him if he dies in action- and only one says yes. Then while he's setting off, he hears of the deaths of all his family, but is only moved at the death of one.

Comparetti (book I quoted in a previous post) mentions four poems. Other sources mention three, which makes me wonder if those stanzas were sung as part of the same rune.