Sources

1) Source: The Ecclesiastical History of England and Normandy: Volume III "He [David] married the daughter of Earl Waltheof, and Judith the king's cousin, and possessed the two counties of Northampton and Huntingdon, which Simon de Senlis held as earl in her right. She bore him a son, named Henry, and two daughters, Clarice and Hodierna" (Data from secondary evidence)
2) Source: The Ecclesiastical History of England and Normandy: Volume III "Ralph De Conches crossed over the sea after his father's death, and received a gracious reception from the king, who confirmed him in his father's English honours and estates. He married Adeliza, the daughter of Earl Waltheof and Judith, the king's cousin, who bore him Roger and Hugh, besides several daughters" (Data from secondary evidence)