I don’t want get involved in this shia sunni debate b/c at the end of the day, we know what happens. But let me ask you this: are the people you mentioned the only family members of the Messenger of Allah 
? Why do you use Hadhrat for his wives? Why don’t you call them Ahle Salam? Why do you people only single out Hadhrat Fatima 
and her descendants (May Allah be pleased with them and shower His mercy on them)? What about the other daughters of the Messenger of Allah ? O, let me guess, you people don’t believe that he had any other daughters.
Also, who said RA is only for sahabs; do you even know what it means? It could be used for any Muslim. It simply means, May Allah be pleased with him/her. One more thing, the word “ahle” in the daroud applies to all the people who has followed/are following/will be following the deen which Allah Ta’ala revealed to Messenger of Allah .