[2] After the death of her mother in 1551, she as well as her siblings were placed in the care of Christina Gyllenstierna and then under her aunts Brita and Martha Leijonhufvud before her father's remarriage to Catherine Stenbock.

[3] In 1556, she and her sisters were given a dowry of 100.000 daler, had their portraits painted and their personal qualities described in Latin by the court poet Henricus Mollerus and were presented on the Dynastic marriage market.

Ostfriesland was chosen because it was strategically placed toward Denmark, and because the Calvinistic Emden was a rival to Lubeck and a treaty could break the domination of the Hanseatic league in Sweden.

Edzard chose Catherine, but the negotiations took a long time, so much so that Gustav Vasa stated in his frustration that it was a blessing that his daughter was at least neither "limped or blind".

Edzard's mother, the dowager Regent Anna of Oldenburg, was afraid that the marriage would lead to Swedish domination, and therefore split the power in Ostfriesland between her sons, something which the king tried to prevent.

[3] In the marriage contract of 12 August 1558, Catherine was assured Berum and Norden as her dower lands and the post of Regent if Edzard should be succeeded by an underage son of hers.

[3] After the death of Edzard in 1599, Catherine lived at Berum Castle and took control over her dower lands Norden, Pewsum, Woquard, Loquard, Campen and Neeuwarden.