Riley Keough won a bittersweet legal victory on Friday, when she was named the sole trustee of the estate of her late mother, Lisa Marie Presley.Things were made official when a judge signed off on Riley's June petition to approve the settlement agreement reached between her, her grandmother, Priscilla Presley, and Michael Lockwood, the Guardian Ad Litem for her two younger siblings. The settlement terms, obtained by ET back in June, will see Riley serve as the sole trustee of her mother's estate and the sub-trusts for her sisters, 14-year-old twins Harper and Finley Lockwood.