The one you put as False Lover John is similar to the one I have heard as The False Knight (not The False Knight On The Road.) It goes by another name too -- there is something about a cat and a parrot named Polly in it.

Again, I don't think its murder, but self-defence, because otherwise he would have tossed her in the drink like the rest of his women. Rather like the old man in Marrowbones (aka Old Woman From Wexford/Mabou) who catches wind of his wife's plan to murder him and drowns her instead.

I think The Flower of Serving Men starts off with a murder by the mother, although the daughter doesn't seem to get any revenge by the end of the song.