In 1647, she married the rich Swedish merchant Magnus Durell, who had been ennobled not long before their wedding.
She followed her spouse to Sweden and settled on his recently acquired country estate, Vallen Castle near Laholm.
The family of her spouse had, two years before her wedding, been given a contract from the crown to provide the Swedish army with knitted socks, which had not yet been fulfilled.
[2] Next, she imported and bought wool, which was distributed to the peasantry of Halland, who were then employed to knit socks for the army on her commission.
[3] The Vallen Castle or Laholm industry was hugely successful, and the contract with the crown belonged to the same family for decades: after the death of Birgitta Durell, it was managed by her daughter Magna Birgitta Durell (1653–1709), then by the widow of her grandson, Clara Sabina Lilliehöök (1686–1758), thereafter by her great granddaughter Magdalena Eleonora Meck (1717–1766), until the family lost the contract and it was taken over by Charlotta Richardy over a hundred years later.