Gustav IV Adolf of Sweden
To further improve the status of Prince Leopold, his half-brother the new Grand Duke Louis I arranged for him to marry his great-niece, Sophie, daughter of former King Gustav IV Adolf of Sweden by Grand Duke Charles's sister, Frederica. Since Sophie was a granddaughter of Leopold's oldest half-brother, Charles Louis, this marriage united the descendants of his father's (Grand Duke Charles Frederick's) two wives. Sophie's undoubted royal blood would help to offset the stigma of Leopold's morganatic birth.