Barbara Campbell was the adopted daughter of David Campbell and his Gallifreyan wife, Susan Campbell.
Biography
Orphaned during the Dalek Invasion of Earth in the 22nd century, Barbara was adopted by David and Susan after the human victory. She was named after Barbara Wright, an early companion of Susan's grandfather, the First Doctor.
Barbara also had two adopted brothers, Ian Campbell and David Campbell Junior (PROSE: Legacy of the Daleks). Some time after David Junior was adopted, David and Susan conceived a child whom they named Alex Campbell. Alex was, on some level, Barbara's youngest brother. (AUDIO: An Earthly Child)