Finding that the singer of "The Blaeberry Courtship" is given a different name in the 1919 book compared with the 1909 article (but then goes back to the original name in the 1928 book) made me curious to see if Mackenzie was in the habit of changing people's names between his JAF articles in 1909, 1910, and 1912 and his 1919 book. (I don't have access to the 1928 book, so I can't compare it.)

As far as I can see, he wasn't.

There are four ballads in Mackenzie's 1910 and 1912 articles that also appear in the 1919 book:

1) "Little Matha Grove"(" Little Musgrave and Lady Barnard") is described in "Three Ballads from Nova Scotia" (1910) as a composite text, mainly collected from from Mrs. Levi Langille of Marshville, with contributions from Mrs. James Gammon of River John, John Langille of River John, and Mrs. Jacob Langille of Marshville. In "Ballads from Nova Scotia (Continued)" (1912), Mackenzie gives some variant stanzas collected from Mrs. Bigney, of Pictou.

In "Quest of the Ballad" (1919), Mackenzie says (p. 87) he collected the ballad from someone introduced as "Easter Ann", who seems fairly clearly to be the same person referred to more formally as "Mrs Levi Langille" in 1910 (the family connections match up), and he gives the first two stanzas of her version (which match those in 1910). Then (pp. 91-92), he says he also collected some stanzas from Mrs. James Gammell and three members of the Langille family. Mrs. James Gammell is obviously the "Mrs. James Gammon" of 1910, and the three members of the Langille family are John Langille and Mrs. Jacob Langille of 1910 and Mrs Bigney of 1912 (described in the article as the daughter of Isaac Langille, hence her local name of "Isaac's Ellen"). So no discrepancy here apart from the difference between "Gammell" and "Gammon", one of which is obviously a misreading or mishearing of the other.


2) "Pretty Polly" ("Lady Isabel and the Elf Knight")
No discrepancy. In 1910, he says this was collected from Mrs. Levi Langille, John Langille (who supplied most of the text), with two stanzas added from David Rogers of River John. Assumingm as above, that Mrs Levi Langille of 1910 = Easter Ann of "Quest", he says the same in "Quest" (pp. 89-92).

3) "Six Questions" (Captain Wedderburn's Courtship)
No discrepancy here either. In 1910 he says he collected it from John Adamson of Millsville
In "Quest" (p. 107) he also says he collected it from John Adamson. The story of how Adamson learned it from his wife who learned it from a friend (p. 110) is the same as in 1910.

4) "The Greenwood Siding" ("The Cruel Mother")
No discrepancy here either. In 1912, he says this was collected from Mrs. Bigney, of Pictou, also known as Isaac's Ellen. In "Quest", starting on p. 102 he says it was collected from Isaac's Ellen. The account in the book of their discussion of the song matches that in the article.

So, for what it's worth, it looks as if the only informant who has a different name in "Quest" compared with the earlier articles is John Henderson / James Isaac Macdonald.