The third picture, which I'm dubbing Biggest Momma, will be directed by John Whitesell, who also directed the second picture.  Joining Martin Lawrence on the cast will be Brandon T. Jackson, who recently appeared in Fox's painfully long named Percy Jackson and The Olympians: The Lightning Thief.  Jackson will be playing Lawrence's nephew.  The story as Variety has it:

"In the latest adventure, FBI agent Malcolm Turner and his 17-year-old nephew, Trent, go undercover at an all-girls performing arts school after Trent witnesses a murder. Posing as Big Momma and Charmaine, they must find the murderer before he finds them."

So not only will we have to see Martin Lawrence in a fat suit dressed as a woman, but also Brandon Jackson in drag.  I sure am excited!  Shooting is set for April in Atlanta.