Pedro married twice, the first time by 17 June 1084[5] to Elo (or Eylo), daughter of Count Alfonso Muñoz and Aldonza González of Trigueros.
She was dead by 17 September 1114, when Pedro made a donation for the good of her soul to the canons of the cathedral of Valladolid, and he appears the next day with his second wife, Elvira Sánchez, whom he may have wed some time before.
Pedro and Elo's children were raised in the household of a lesser nobleman: that of Citi Álvarez and his wife Froilo, who were duly rewarded for their services with a grant of land.
The environs of Valladolid formed the outer limits of the Kingdom of Castile at his time and Pedro was responsible for the repopulating of the region between Liébana and Cuéllar.
[8] Around 1087, at the time of the marriage of Alfonso's eldest daughter and heiress apparent, Urraca, to Raymond of Burgundy, the king appointed Pedro to be her guardian (tutor), and she stayed at his court according to the later Primera Crónica General (late 13th century).
[12] In 1143, Sancho Ansúrez, Pedro's grandson by his daughter Urraca, introduced the Premonstratensian Order into Spain when he became abbot of Fuentesclaras, moved to Retuerta in 1146.