Spaw,
I just looked on Emmylou's recording and its just credited to Phillips. However, I'm about 99.99% sure that she learned it from Hazel & Alice's album because there are a couple of other songs from it that she recorded around that time.
I also just looked on my original copy of the Phillips songbook. It was published in 1973, the same year that Hazel & Alice recorded that album.
There was a slightly earlier recording of "Green Rolling Hills" by Bottle Hill that did not include the third verse.
Mike Regenstreif