Fools rush in where wise men fear to tread.
The rulers of Savoy seem to have been overly fond of the name Beatrice (Beatrix) - Amedeus IV had a sister and *two* daughters by that name, and that's just for starters.
The Beatrix who married Raymond Berenger was his sister.
His daughter Beatrix the elder married the two Manfreds.
As to Beatrix the younger: m firstly (21 Oct 1268) PIERRE "le Bouvier" de Salins Seigneur de Châtelbelin, son of JEAN I "l'Antique/le Sage" Seigneur de Salins [Bourgogne-Comté] & his second wife Isabelle de Courtenay (-[21 Jul 1272/29 Apr 1274]). m secondly (1275) as his second wife, Infante don MANUEL de Castilla y León, Señor de Escalona y Peñafiel, son of FERNANDO III “el Santo” King of Castile & his first wife Elisabeth von Hohenstaufen (Carrión de los Condes 1234-Peñafiel 25 Dec 1283, bur Uclés, Santiago convent).
There was also a *niece* Beatrix (daughter of his brother Pierre), who m firstly (Betrothed 4 Dec 1241, [before 22 Apr 1253]) GUIGUES Dauphin de Viennois Comte d'Albon, son of ANDRE Comte d´Albon [Bourgogne-Capet] & his third wife Beatrice di Monferrato ([1225]-[Aug/Nov] 1269, bur Chartreuse Abbaye de Prémol). m secondly (contract 2 Apr 1273) as his second wife, GASTON VII Vicomte de Béarn, son of GUILLEN de Moncada Vicomte de Béarn & his wife Gersende de Provence [Aragon-Barcelona] (1225-26 Apr 1290).
https://fmg.ac/Projects/MedLands/SAVOY.htm