sounds like it's working really well for her, Lece. She's getting exactly what she wants every time.
With a total of 7 other children around constantly, she's found how to get attention - by screaming. She's found the exact pitch and volume that gets a response every time.
More than likely the other children have taught her to scream, next time she has a lot of children around take a look when they dont know you are around, it sounds like learned behavior.