Re Richie post-
As noted earlier, the Piper collection needs to be re-checked. There could be more data.
Many of us, in going over old papers, or trying to remember when or where we got them, add dates which we 'think' are correct- the MS could be 'authentic' but the added dates the product of faulty memory. On the other hand, we know that the song pre-dates 1889, so the notes could be OK. We can't know whether the notes refer to a singer the writer heard, or printed material that he saw.

Previously, John Garst posted Lady in Love, from Wehmann's Collection of Songs, no. 24, 1889. The verse content is the same as "Red River Valley." Wehman published collections, so the song is older than that; but how much older, and which valley is meant, if any particular one, is not yet known.

(The Gaelic is late and has nothing to do with the origin of the song. Reminds me of the Chinese cook I heard in a small Alberta town who translated cowboy and pop songs into Chinese and sang them as he cooked in his cafe.)