The basic question of the thread is: what's the best way to get French relations with North America Natives to deteriorate far enough that by the time of French-Indian war the Indians will want nothing to do with the French?
The problem I see with this idea is that the Iriqouis had already given a huge defeat to the Huron and other great Lakes are tribes. They created the Iriqouis Shatter Zone, totally depopulating the area around lake Huron ,the eastern shores of Lake Michigan, and much of the area between the Ohio river and the Great lakes were totally empty. They also had adopted a huge number of captives, Jesuit priests in the area estimated that many "Iriqouis" villages were majority Huron in ethnicity. So, the idea you outline above (while good) really couldn't have worked, as the Iriqouis could simply not adopt (I take issue with your labeling of conquered tribes as a "subservient underclass" the adoption process was more equitable then you suggest, although this is a minor quibble any more) many more Huron. Either way, by the time of the French and Indian war, the major native ally of the French was the ottawa. not the Huron (who had been scattered across the Great lakes region in a diaspora).You could have the Iroquois inflict an even greater defeat upon the Huron during the Beaver Wars of the mid-1600s. If the Hurons were completed defeated and absorbed into the Iroquois as a subservient underclass (as was common with defeated tribes) than over time they would be integrated into a greater Iroquois society. This larger more powerful Native Nation would be a force to be reckoned with. While they would be more likely to side with the French (less demographic pressure and less arrogant attitudes), it is not inconceivable that the French could make a major diplomatic error. Perhaps a massacre occurs during one of the prior wars which turns the Iroquois/Huron against them. As I'm related to a Seneca and Joseph Printup, I have a lot of material concerning Anglo-French-Native relations. I'll look around for a good POD if you wish.
Benjamin
A POD that's close to the French-American war itself would be best, since I don't want too many pesky butterflies flying around. My current plan is to send someone with exceptionally bad understanding of the natives to govern the French colonies, but that may need something to supplement it.
How about this lousy governor decides the Iroquois, as English allies, need to be rooted out, but doesn't want to drag French troops into a war with England. He concocts a plan to start a war between a number of French allied Indians to attack the Anglo-allied nation, but those that go see their people slaughtered by the confederacy, and those that don't want nothing to do with the French governors, especially their wars.
The problem I see with this idea is that the Iriqouis had already given a huge defeat to the Huron and other great Lakes are tribes. They created the Iriqouis Shatter Zone, totally depopulating the area around lake Huron ,the eastern shores of Lake Michigan, and much of the area between the Ohio river and the Great lakes were totally empty. They also had adopted a huge number of captives, Jesuit priests in the area estimated that many "Iriqouis" villages were majority Huron in ethnicity. So, the idea you outline above (while good) really couldn't have worked, as the Iriqouis could simply not adopt (I take issue with your labeling of conquered tribes as a "subservient underclass" the adoption process was more equitable then you suggest, although this is a minor quibble any more) many more Huron. Either way, by the time of the French and Indian war, the major native ally of the French was the ottawa. not the Huron (who had been scattered across the Great lakes region in a diaspora).
The real challenge here I think is to prevent the formation of the Grand anti-Iriqouis alliance of the late 17th century, composed of those tribes defeated by the Iriqouis (mostly Algonkians) and the French.
As for the OP, I'm having a difficult time thinking of a way to get the native nations to go against their best interests and side with the English as a monolithic group. The English were by far the greater threat to the natives and while some, like the Iroquois, tried to game the system it was always a losing proposition and they usually recognized that.
Benjamin
The basic question of the thread is: what's the best way to get French relations with North America Natives to deteriorate far enough that by the time of French-Indian war the Indians will want nothing to do with the French?