1-hetal may kidnap ria and beg avni to take her place and save her and our avni may agree
2-hetal kidnaps ria and dayaben couldnt find her so daya begs avni to save her respect by taking ria s place
3-shwetha may kidnap ria thinking her as avni so again daya or hetal begs avni
4-neela makes shwetha beleiev avni and does it together
5-neela and avnis plan(unlikely but they may do it as a last resort)
6-neela does it to protect avni frm neil(highely unlikely)
7-neela and neil plans it to expose daya
gyus which one may happen and do share some more theories...