She had two older half-sisters from her father's first marriage, an elder Beatrice and Margaret.

Upon Peter's death, Beatrice had to renounce her claim on Savoy along with the consent of her mother in favor of the succession of her other uncle as Philip I, Count of Savoy, in the article (dated 21 October 1268) she is referred to as Contesson [2] possibly to distinguish her from her older half-sister of the same name.

A charter dated 11 August 1266 by Pope Clement IV presumably tells of Count Philip donating property to his niece "B" most likely referring to Beatrice.

Beatrice firstly married on 21 October 1268 to Peter of Chalon, Seigneur de Châtelbelin, son of Jean l'Antique.

A second marriage in 1275[a] took place with Manuel of Castile;[7] this was a second marriage for both parties, Manuel's first wife Constance (sister to Beatrice's one-time fiancee James) had died leaving him with two children.