Speaking strictly as someone who knows absolutely nothing about the matter except what he's read in these threads, I wouldn't say that the above necessarily 'proves' anything, if there is a real contention. Questions could be asked: Is this Kiely remembering accurately? Is it possible that Kelly or someone else had suggested the melody or actually sung it to Kavanagh previously, and he was trying to decide if it worked or not? Does Kiely have some personal reason for not wanting to see Kelly get any credit for the song? Etc.

(I'm not trying to shoot down your contribution; just thinking out loud).