Princess Louise of Denmark (1875-1906) married Prince Friedrich of Schaumburg-Lippe (1868-1945) and had three children by him:
1) Marie Louise (1897-1938 ) who married Prince Friedrich Sigismund of Prussia (1891-1927) and had two children by him, a son and a daughter. The son, Prince Friedrich Karl of Prussia (b. 1919) married twice but fathered no children. The daughter, Princess Louise of Prussia, married morganatically, had one son who lives in New York, but he did not have any children from his marriage either.
2) Christian (1898-1974) who married his first cousin Princess Feodora of Denmark (1910-1975) and had 3 sons and 1 daughter. In fact his son Prince Wilhelm (b. 1939) is a regular at the Danish court where he maintains very good relations with his cousins Margrethe and Elisabeth.
3) Stephanie (1899-1925) who married Fürst Viktor Adolf of Bentheim und Steinfurt (1883-1961) and had 2 sons by him, one died during the Second World War, the other married but had no children.
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As for Ingeborg, Trond Norén Isaksen, a well-respected Norwegian biographer, has covered her and her children in various, marvelous by the way, biograhical articles in past issues of the EUROPEAN ROYAL HISTORY JOURNAL, which were thoroughly researched and handsomely illustrated!
Arturo Beéche