Thanks for your thoughts, George and no, I don't think you've confused the issue at all. Joe's right, it's very true that as much information as possible is the best way to go.
Now, I do have Fiona's address, so I could conceivably write to her and ask if she knows the origin of the two verses. It may take quite a while to get a reply, so before I write to her, I'd like to know in advance if those of you who have commented think it's worth the time & trouble to try and find out. . . ?
As far as authors go, here's another example: I found a tune in the Roche Collection of Irish Music that is entitled "The Morning of Life" and credited to a certain O'Carolan. This tune is NOT included in the "Complete Works of O'Carolan", but sounds very much like it could be a Turloch O'Carolan piece. What to think??