See Brother, Sister. All are different parts of self. According to Freud, this is very often a symbol for genitals. Older siblings, according to Jung, point to more developed parts...

1. When a brother or sister shows up, it indicates unre­solved conflicts with the person.2. Reflection of a good quality or qualities that one should incorporate in oneself.

The appearance of siblings in your dream may be a direct representation of them or it may actually stand for something else in your life. Some dream analysts believe that...