first rashi taunted gopi. at that time koki told her though gopi might be her younger sis, she is the jethani of the house, so she has more respect and importance
second rashi's kalakari on hetal and koki
through this is rashi trying to show koki that she is just like her. it is sure that koki may say something to hetal. at that point rashi might point out that hetal is jethani. there by trying to create a rift.