The youngest, Dorothea Elisabeth, was rumoured not to have been the king's child; Her children intermarried with the nobility of Denmark, Corfitz Ulfeldt and Hannibal Sehested being among her ambitious sons-in-law.

Previously, Kirsten's son Count Valdemar of Schleswig-Holstein, had shown promise, becoming engaged to Tsarevna Irina Mikhailovna Romanova, daughter of Michael I of Russia.

The alliance was prevented by Danish objections to Valdemar's conversion to the Russian Orthodox Church, yet the king's disappointment on the betrothal's rupture was believed at the time to have hastened his death.

One of Kirsten's daughters, Countess Leonora Christina, distinguished herself by an internationally adventurous life, followed by imprisonment for decades in Denmark's royal dungeon, and by the posthumous publication of her memoirs, still well regarded both as Scandinavian prose and as early feminist literature.

Despite the turmoil of her parents' marriage and the conflicts between her brothers and brothers-in-law, according to her own writings Leonora Christina's youth and early married years at the Danish royal court were happy.

In 1627, Kirsten fell in love with a German cavalry captain in her husband's service, the Rhinegrave Otto Ludwig of Salm-Kyrburg (1597–1634).

Supposedly, after seeing two maids sleeping outside her locked door, he got a footman to engrave the date on a stone and did not have sex with Kirsten again.