Other than book and movie reviews, there isn't much information on the Ya-Ya Sisterhood online. But here's a bit that hints at its Indian origin:
Divine Secrets of the Ya-Ya Sisterhood (film)
Verifying the Sisterhood's origin
With all the New Age nonsense on the Web, I thought it would be easy to verify the Ya-Ya/Hopi connection. But it wasn't.
Fortunately, I'd read Frank Waters's Book of the Hopi. It devotes a chapter to the Ya Ya ceremony, which the Hopi consider a form of evil. Writing in 1963, he said:
Summing up Waters's book
Book of the Hopi was one of the first books I read about the Hopi 20 years ago. Initially I was impressed with the depth and breadth of Waters's knowledge. In retrospect, he sounds like a New Ager or Castaneda disciple who swallowed what he heard uncritically. And you have to suspect an outsider's ability to understand another culture.
I wonder what the Hopis think of his deconstructing their religion and revealing their sacred beliefs. It would be interesting to read their critique of his book. Somehow I doubt they appreciated it.
Anyway, I trust people who search for the origin of the Ya-Ya Sisterhood now will find this posting. The Sisterhood is another of our millions of words and ideas
For more on Hopi beliefs, see Hopi Mask in American Dad! and Rainbow Gatherings Based on Hopi Prophecy?