Sorry but i disagree with u
i wont say shes jealous but shes definitely sad that she couldnt enjoy the perks of being a teenager while navya can .poor Renuka i feel sorry for her . marriage n motherhood at 22 thats too because of parental pressure .she never had lived her life on her own terms it was always her dad aur dadi deciding every thing for her so its obvious she would feel dejected as navya gets something that she craved but never got .
n as far as the sibling rivalry considered her planning that dumb rama is too far fetched according to me