YOU SAID:

I went to the store with my half-step-sibling and she brought her adopted twin

INTO JAPANESE

私は半音の兄弟と一緒に店に行きました、そして彼女は彼女の養子の双子を連れてきました

BACK INTO ENGLISH

I went to the store with my semitone brother, and she brought her adopted twins

INTO JAPANESE

私は半音の兄と一緒に店に行きました、そして彼女は彼女の養子の双子を連れてきました

BACK INTO ENGLISH

I went to the store with my semitone brother, and she brought her adopted twins