Both vanished without a trace in 2001.
The two girls were 10 and 3 years old when they disappeared from their apartment near 35th and Cottage Grove, while their mother was at work.
Police launched one of the biggest manhunts in Chicago history, mostly turning up nothing.
Back in May, a Texas woman claimed to be Tionda Bradley, but the heart-broken family quickly revealed she was lying.
A vigil will be held at 48th and State streets at 5 p.m. Saturday.