Yes, he has 4 brothers and sisters.
Mr Mubarak has three brother - one is called Issam. He also has one sister.
technically speakking yes because ur parents are legally responsible for both?? if not she still is considered ur sister
If your sister goes with your brother then it's incest and they would both be your siblings. If a girl is dating your brother and they get married this would make her your sister-in-law.
The oldest sibling was Reuchlin, followed by Lorin, Wilbur, Orville, and Katharine.