Why Wasn't She In 'What's Love Got To Do With It'?

When they made a movie about Tina Turner's life why didn't they bother to include her sister, Kathleen Turner? Did they have a falling out? Even if they did, I'm sure it was nothing so bad that they had to completely ignore the fact that Kathleen was Tina's sister. If they did have a fight, I hope one day they can get pass their differences and make up like family should. One day I really hope to see the Turner sisters reunite.