von Alvensleben
Altmark · Saxony-Anhalt
Arms: Wikimedia Commons, nach GHdA-Adelslexikon Bd. 53 (1972), gemeinfrei
Karin and her sister Luise, who married into the house of von Hülst, were daughters of Friedrich von Gerlach of Rohrbeck. For the von Alvensleben this is the second connection: Elisabeth Luise von Alvensleben had earlier married into the family.
One of the eight castle-holding noble houses of the Altmark (see "Families That Married In" for the fuller family history and the first connection, through Elisabeth Luise von Alvensleben).
Sources: Degener Verlag, Deutsches Familienarchiv vol. 160 »von Gerlach – Lebensbilder einer Familie« (in German); Wikipedia articles on the families named; Wikimedia Commons (coat-of-arms images). Given to the best of our knowledge. Jürgen von Gerlach: von Gerlach. Lebensbilder einer Familie in sechs Jahrhunderten (Deutsches Familienarchiv 160), Insingen 2015 (in German). All sources. For corrections or additions, please contact the family administration.