My thoughts on why dadoo put the stipulation in the will.
I think dadoo knew that there was a good chance that Raghu will transfer the property back to Shivani upon his death and was afraid that j&M will manipulate Shivani again, that's why this stipulation to do what he could to prevent it.
My feeling is that dadoo put the clause about Shivani staying with Raghu for 3 months not only for their feelings to develop like Latha suggested, but also he knows that Shivani is very naive and everyone did everything for her. Now that he is gone, he wants her to "grow" and learn life lessons with someone he can trust and that being Raghu and I think he sensed that Raghu's mom is good and will take care of Shivani and help her.
He knew that Raghu and Shivani who are honest and caring will respect this stipulation and abide by it as it was his last request. I don't think Raghu or Shivani really care for the property they don't seem greedy.
Don't know if I made any sense. just my thoughts. 😊