Very interesting post, Chicago85. I knew a tiny bit, too little, about the terroristic debacle of Oklahoma in the 1920s, but nothing about Misty Upham's death.
I need to read this play and hope that I might see a decent production of it someday. History is what hurts.

I had no understanding of why the family thought the police caused her to run. The story on my local media was so fragmented and gave so little detail it made it seem like the family just needed someone to blame. They made them sound absurd.

It was set in Osage County. Julia Robert's husband remarks on what happened to the Indians there and also in the commentary track Ewan Mcgregor says the same thing.
The Osages were placed on the most worthless crap land whites could find. UNTIL OIL WAS DISCOVERED IN THE 1920's. Then began what has been labeled a reign of terror. Whites decided Indians needed "Guardians" if they were 50% or more native American. Quickly some 60 suddenly wealthy Osages were murdered by a gang and others for their oil rights. This was one of the first sucesses by J Edgar Hoover and the new FBI. They had to come in because the county officials were so utterly corrupt.
Even then only three convictions were obtained and they later got parole over the objections of the Osages.
Native Americans throughout Oklahoma were murdered for their land. Especially orphans by their so called guardians who were corrupt lawyers selected by corrupt county judges.
By the way the native American actress in this movie just died. There is controversy about it. Her family said she stopped taking her medication to be a care giver for her father who had a stroke. Apparently someone called the police but they didn't do anything. Her family found her dead at the foot of a cliff.
They said she had been arrested once before for her emotional condition and had been handcuffed and put in the back of the police car. The police then laughed at her and made faces at her through the window.
She was apparently so afraid it would happen again she fled into a wooded area where a ravine was concealed by foliage. The police are trying to
say it was suicide to they can close the case.
I don't know everything. Neither does anyone else

Johnna is Native American because it's to show that people like Johnna - kind, generous, good people inhabited this land hundreds of years ago and are responsible for making it great, basically, and people like the Weston family (Vi in particular) basically ruined it all. That's what I take from it, anyway. The character of Johnna is expanded considerably in the play.