The lawsuit was filed in U.S. District Court in Chicago.
Jacque Hollander told The Associated Press Wednesday that she helped create the trust to help needy children.
Hollander's attorney, Donald Rosen, said Brown borrowed money from the trust for his personal use, making it invalid. He says Hollander, the only surviving partner, should control it.
Former Brown trustee Buddy Dallas backs Hollander's claim, but both have been criticized by attorneys pushing a long awaited settlement over how to parcel out Brown's wealth.
A South Carolina judge has threatened to hold Dallas in contempt of court for not turning over financial records.