Princess Calixta of Lippe
Princess "Calixta" Agnes Adelaide Irmgard Helene Caroline Elise Emma of Lippe (14 October 1895 - 15 December 1982) was the wife of Prince Waldemar of Prussia, eldest son of Prince Henry of Prussia.
Prince Bernhard of Lippe (1872–1934)
Prince Bernhard of Lippe (Bernhard Kasimir Wilhelm Friedrich Gustav Heinrich Eduard; Oberkassel, 26 August 1872 – Munich, 19 June 1934) was a member of the Lippe-Biesterfeld line of the House of Lippe.
He is most notable for being the father of Prince Bernhard of Lippe-Biesterfeld, the prince consort of Queen Juliana of the Netherlands.
Frederick Charles Augustus, Count of Lippe
Count Frederick Charles Augustus of Lippe- Biesterfeld( 20 January 1706 in Biesterfeld – 31 July 1781 in Friedrichsruh) was a Count of Lippe and Lord of Lippe- Biesterfeld, Sternberg and Schwalenberg and a Knight of the Order of the Red Eagle.
He was the eldest son of Rudolf Ferdinand of Lippe- Sternberg- Schwalenberg( 17 March 1671 – 12 July 1736) and Louise Juliane of Kunowitz( 21 August 1671 – 21 October 1754) and the grandson of Jobst Herman of Lippe- Biesterfeld.
Prince Waldemar of Prussia (1889–1945)
Prince Waldemar William Louis Frederick Victor of Prussia (20 March 1889 at Kiel – 2 May 1945 at Tutzing, Bavaria) was the eldest son of Prince Henry of Prussia and his wife, Princess Irene of Hesse and by Rhine.
Julius, Count of Lippe-Biesterfeld
Julius, Count of Lippe-Biesterfeld (2 April 1812 – 17 May 1884) was Count of Lippe-Biesterfeld from 1840 to 1884 and father of Ernest II, regent of the Principality of Lippe.
He is an ancestor of King Willem-Alexander of the Netherlands.
Armgard von Cramm
Baroness Armgard von Cramm( 18 December 188327 April 1971) was the mother of Prince Bernhard of Lippe- Biesterfeld, Prince consort of Queen Juliana of the Netherlands.
Friedrich Count of Lippe-Biesterfeld
Friedrich Count of Lippe- Biesterfeld( 10 May 1852 Mechernich- 15 August 1892) was Count of Lippe- Biesterfeld.
Prince Aschwin of Lippe-Biesterfeld
Prince Aschwin of Lippe- Biesterfeld( 13 June 1914 – 14 May 1988) was an expert in Chinese painting and Indian sculpture and curator at the Metropolitan Museum of Art in New York.
He was the younger brother of Prince Bernhard of Lippe- Biesterfeld.
Ernest, Count of Lippe-Biesterfeld
Ernst, Count of Lippe- Biesterfeld(" Ernst Kasimir Friedrich Karl Eberhard"; 9 June 1842 – 26 September 1904) was the head of the Lippe- Biesterfeld line of the House of Lippe.
From 1897 until his death he was the regent of the Principality of Lippe.
Countess Adelaide of Lippe-Biesterfeld
Countess Adelaide of Lippe- Biesterfeld( 22 June 1870 – 3 September 1948) was the eldest child of Ernest II, Count of Lippe- Biesterfeld and Countess Karoline of Wartensleben.

Question: Who is the mother-in-law of Princess Calixta Of Lippe?
Answer: Princess Irene of Hesse and by Rhine