Kids have a way of seeing and hearing things that they shouldn't. Though Harini wasn't shown in CN (maybe bcoz of pandamic laws) and shipped to a hostel, what if she has heard and seen a few things about P. Her first reaction to P was awesome. When her Sai Mami comes back would she be able to confide in her and reveal P's darkest secrets.
What if P is aware that Harini has her secrets and the "kheer" offer is her way of bribing and keeping her on her side.