I don't think Kastur knew Saroj hate or dislike her. Everybody even the whole Desai family think Saroj is stern but nice and will take care of Kastur and there was never a time Saroj has made them to think otherwise. The only people who knows Saroj true feelings is Bhanu & Mohan.
There is nothing that Saroj has done to maker Kastur feel she doesn't like her. There has been misunderstanding due to something or the other but there is nothing direct that Saroj has done to Kastur that indicate not liking or hating unless I miss something
