Bani Hashim (the family of the Prophet) are entitled to Sahm Sadat if they are poor. The grand children of Ameerul Mo'mineen Ali (AS) are called Alawi Sadat while grandchildren of Aqeel ibn aabi Talib are called Aqeeli Sadat and grandchildren of Jafar ibn Abi Talib are called Jafari Sadat.
Wassalam.