Amitabh Bachchan writing the letter to his grand daughters. Picture courtesy/ Amitabh Bachchan Twitter account

Megastar Amitabh Bachchan has penned a heartfelt letter to his grandaughters Navya and Aaradhya, telling them to be independent and strong women as they grow up. Navya, 18, is the daughter of Bachchan's daughter Shweta, while four-year-old Aaradhya is his son Abhishek's child.