"Berengar's grandfather was Gebhard I, Count of Sulzbach (died 1071), who married the daughter of Count Berengar I of Sulzbach. Gebhard I may have been the son of Herman IV, Duke of Swabia (died 28 July 1038), but this is not certain." https://en.wikipedia.org/wiki/Berengar_II_of_Sulzbach
"[RICHWARA (-before 1056). According to Wegener, Richwara wife of Berthold [I] [von Zähringen] was the daughter of Hermann IV Duke of Swabia[221]. However, this seems unlikely from a chronological point of view. Richwara gave birth to five children, presumably between [1045/55], so is unlikely to have been born later than 1030, when her supposed father was only 15 years old and her supposed mother about 10. m as his first wife, BERTHOLD I von Zähringen, son of BEZZELIN von Villingen & his wife [Luitgard ---] (-Limburg 5/6 Nov 1078, bur Hirsau). Duke of Carinthia 1061. Marchese di Verona 1066.]" https://fmg.ac/Projects/MedLands/SWABIA.htm#_Toc359919998
"...the title could certainly apply to Hermann I von Kastl: he is very likely the son of Duke Hermann IV of Schwabia and Adelheid of Susa and thus a grandson of Duke Ernst I."
(der titel konnte durchaus auf hermann i von kastl zutreffen: Er ist mit hoher Wahrscheinlichkeit der sohn herzog hermanns iv von schwabeb u. der Adelheid von Susa und damit ein Enkel von Herzog Ernst I.) [Footnote #4 beginning on bottom of p. 635] https://www.google.com/books/edition/ZBLG_2019_Band_82_Heft_3/WiwyE...