Chaka Khan Wins 8 More Years of Grandma Duty

12/16/2011 4:00 AM PST

Chaka Khan just signed herself up for the most stressful years in a parent's life -- agreeing to take permanent custody of her 10-year-old granddaughter ... TMZ has learned.

According to new docs filed in L.A. County Superior Court, the order went through Wednesday -- granting Chaka permanent guardianship over her granddaughter Daija Jade Holland. Chaka's sister Tammy McCrary was awarded co-guardianship.

TMZ broke the story ... Chaka won temporary custody back in September -- claiming the girl's parents (including her son) are drug addicts ... and are incapable of taking care of her.

A sad story ... with a happy ending.