Anna Sybille Reventlow was the daughter of Lieutenant-Colonel Carl Rudolph Schubart and the sister of Charlotte Schimmelmann. She married J. L. Reventlow in 1778 on the estate of Brahetrolleborg, where she reformed nursing and health care and, after her husband’s death, took over the management of the barony’s educational system, college, and boarding school.
Sybille Reventlow corresponded with numerous people. Her most continuous and extensive correspondence was with Louise Stolberg: Efterladte Papirer fra den Reventlowske Familiekreds 1770-1827, vol. 9, in a selection compiled by L. Bobé, 1895-1932.