Theory: Grandma is just a Toad Servant

Abstract
Super Mario RPG: Legend of the Seven Stars' "Grandma" is not related to Peach: she is just a Toad servant.

Arguments

 * Argument 1: Super Mario RPG: Legend of the Seven Stars is known for its mistranslations.


 * Argument 2: The Japanese name for "Grandma", ばあや, translates to "wet nurse" or "old housekeeper".


 * Argument 3: In the Nintendo Player's Guide for SMRPG, "Grandma" is referred to as "Chambermaid".


 * Argument 4: If it was intended for "Grandma" to be related, why isn't her name the Japanese term for grandma or similar?