Payal has cunningly usurped moral rights over Shiv, as his Guru Ma and adopted Mom against his little heart's wishes.He would've jumped in joy if it was Kanak who was forming a lifelong bond.
Imo , for him Kanak will be his Dadusa's wife always and her struggle will be to do the right thing for him as his Bhabhisa or as an outsider.
Hmm.. Kanak could also come back to Uma for Shiv's sake as Payal & Mom's games get dirtier.