I think this idea is given to dadi by vishwa
vishwa might be behind all this drama and acting good infront for manjari and as also yug is against marrying gauri
dadi plans might be actly this is same seq shown in choti bahu
dadi and gauri will be together in this plan
gauri might act as if she is changed or positive and took part in all functions and secretly tries to make all those rasams on her too like mehendi,haldi and all like uttaran
on marriage day dadi and gauri will plan to hit kali and lock her in a room and gauri will exchange her place in mandap
even gauri will get same bride dress
but bcz of confusion dadi or some of there members in plan will hit gauri thinking its kali
kali will be in mandap and marriage will be done dadi and may be viswa too if he is part of this plan will think its gauri in ghunghat
but after marriage they will be shocked too see kali in the ghunghat
vishwa might be showed last that he was also part of this plan with dadi and it might be actly his idea