I'm a little confused...
What are you talking about when you say "The Native Americans"? I know two who would love horses, and I know a lot of people with native in them that adore horses as well. I also know a couple blue bloods that have nothing, and want nothing to do with horses. Its just ancestroy to them.
Do you want to return them to the land? Give them to a reservation? In my opinion and experience, Native Americans are just normal people. There are accountants, businessmen, equestrians, waitresses, etc. They haven't "lost" or "forgotten" their horse sense. Some natives were avid horsemen, others were avid butchers, seemstresses, farmers, whatever have you.
Native American equestrians don't know any less than what whites do, and they learn everything the way everyone else does. Through lessons, trial and error, and practice.
I'm sure you didn't mean it in an insulting way, but it is a bit insulting. Many of my native friends have stood up the way they need to without using horses. What is it that you planned on teaching native equestrians that they already didn't know? A white person attempting to teach a native about how to recreate and use their own heritage is a bit of an insult.
All in all, I guess I just don't understand the question. She could probably sell or donate the horses to an indian reservation. You can put them on craigslist to sell them, or dreamhorse.