I was reading your thread and thought these links might add some interest.

http://www.plainsfolk.com/songs/song4.htm
http://www.plainsfolk.com/
Some information about Manitoban culture and history that might shed some light on the confusion here.
Manitoba was originally occupied by the cree people of First Nations, Canada. Thier culture carried a highly developed capacity for sharing. Cree culture teaches that the power of this sharing capacity would ultimatly absorb all others whom it contaced. In this way the French who settled in Manitoba soon became the French-Metis, and the Scotts became the Scotts-Metis. The Riel Rebellion succeeded in establishing an independant (if briefly) Metis (which literally means "Mixed Blood") Nation.

Within this cultural cocktale there resides all of the peices that you have been discussing.

Half-breed was a term which was in common usage (including government publications) from the time that Manitoba was still a part of the former Rupert's Land and up untill the 1970's. Many Metis appear white, aboriginal, or show a mix of traits. The singer appears in each of these forms (from a white girl, to a dark maiden) depending which version you look at. The subject however, remains consistantly blue eyed (british).

That there might be some passive/agressive behavior as described in the testimonial from your list:
"Some years ago a friend whose home was in Montreal told me that at one time a crack Canadian regiment had been stationed in the Red River Valley locality. The officers were well thought of socially, but seem to have philandered among the Indian girls to some extent. The white girls, of course, resented this, and at a farewell ball given to the officers on the occasion of their transfer, the young lady who had composed this song rose and sang it, much to the embarrassment of the ones at whom it was aimed."

Frankly this is very typical Manitoban style (chuckels) not only the way in which it was delivered but the aditional practice of adopting a popular melody, making it our own and creating a double entandre to target a specific audience (in this case the british troops in occupation). This practice is rooted in a tradition of sharing, and is apparent in our music, theater and humor to this day.

The song "Red River Vally" that is sung on the prairies originated out of this specific cultural heritage and though we may not be able to take credit for the muse (if the melody was given to us from somewhere else), I would challenge that the meaning and intent have dramatically altered from the original lyric if viewed from it's historic context and that it becomes a different song than the one being sung in texas or in church.

A parlor song??? a love song??? these guys had thier way in the bowers of the entire Red River Vally!