She is married to Andrew Calderwood.
They got married on December 10, 1799 at Riccarton, Ayrshire, Scotland, she was 23 years old.Sources 1, 3
The book describes part of the authors life, visiting various family residences, on her travels around Ayrshire. Jean/Jane Stevenson's Grandmother, Mary Galt, is Jean Galts sister, her Great Grandmother is Helen Young, Great Grandfather is John Galt.
1776 GALT, AGNES (Old Parish Registers Births 584/ 10 126 Craigie)
Agnes daughter to John Galt in Harelaw was baptised 7 March (1776)
1799 CALDERWOOD, ANDREW, AGNES GALT(Old Parish Registers Marriages 10/12/1799, 11/ 10 391 Riccarton)