- Daughter of Juán Fernández de Andeiro and Doña Mayor Fernandes de Moscoso.
- Married Álvaro Gonçalves, the son of Gonçalo Vasques de Azevedo, who sided with Juan I of Castile in his claim for the Portuguese crown. Álvaro Gonçalves, however, remained faithful to to the Master of Avis. [João1, ch. 67: 75]
Chronicle entries in which Sancha de Andeiro appears:
Crónica de D. Fernando, ch. 134