They are brother and sister.

他们是兄妹。

youdao

I love my sister and brother, They are lovely.

我爱我的兄妹们，他们很可爱。

youdao

My brother and sister are here. They visit every week.

我的兄妹来了，他们每星期都来访。

youdao

Today, like on Tuesday, Oscar's father Henke, brother Carl and sister Aimee are seated as close as they can be to the Olympic and Paralympic athlete - near enough to reach forward and hold his shoulder during the frequent occasions when he has been overwhelmed by emotion.

BBC: Oscar Pistorius: Drama of the courtroom

Her sister and brother are finishing high school, thanks to the same charity, but they too fear they'll never be able to go to college.

CNN: Behind the Scenes: Inner city kids travel to South Africa