Steinvör's parents were Sighvatr Sturluson, leader of the Sturlungs, and Halldóra (daughter of Tumi Kolbeinsson, head of the Ásbirningar family clan).
Hálfdan was, according to the Sturlunga Saga, a peaceful man who preferred the calm of his own farm to getting involved in contemporary politics.
When her brother Þórðr kakali returned four years later from Norway to take revenge and restore the lost power of the Sturlungs, he first sought refuge with his sister at Keldur.
According to Þórðar saga kakala he reckoned that Steinvör "who was a very powerful woman, certainly would prompt her husband to act".
Open assault at arms was averted when Steinvör and bishop Sigvarðr Þéttmarsson were chosen as mediators.
She then gave the estate Grund to her son-in-law Þorvarðr Þórarinsson of the Svínfellingar family clan, and set him to take charge of Þórðr's goðorð in Eyjafjörður.