There seems to be a misunderstanding. The character "Sweet Brown" is a real person who went viral in 2012 for her story about a fire in her apartment building. "Lemon Brown" is a fictional character created by Walter Dean Myers in his short story "The Treasure of Lemon Brown."
These are two distinct individuals, and there is no connection or reason why "Sweet Brown" would ever be called "Lemon Brown."
It's possible you are thinking of another story or character. Could you provide more context or details?