Mayor was the daughter of Fernán Ruiz de Biedma and Marina Páez de Sotomayor. The date and place of her birth have not been found.
She had two marriages/partners. Her first husband was Fernando García de Sanabria. They were married, but the date and place have not been found. Their two known children were Teresa (c1285-?) and Pedro (?-?).
Her second husband was Huan Alvarez Osorio. They were married, but the date and place have not been found. They had no known children.