The fear! Dorothy's little sister?

Dorothy is begged to prepare dinner for Chacha, Riiya, and Shiine. They all go to a grocery store where Dorothy meets her younger sister Doris. Doris disguises herself as Dorothy and traps Dorothy somewhere when they are eating dinner. However, they figure out it isn't Dorothy because of the way she was acting. At the end Cha Cha uses holy up on Doris's Guard.