as we know that zarina wahab is playing that role.
being a senior actress,i think that one should be a pivotal role.she wouldn't have accepted it if it was an insignificant one.
after scratching my head,i come to predict that she must be kuku bhatia's 1st wife,sikki's real mom.
i think after sikki was a baby,kuku must have deserted her when she was preggie with sultan.and hence sikki doesn't remember anything.(u can interchange sultan n sikki's places in above 2 lines.)
and now sultan n his mom r back with vengence to snatch everything from radhaji and RK as they r under the impression that radha-RK duo stole kuku from them.