Question: Who is Helvig Of Schauenburg's maternal grandmother?

Knowledge 1: Helvig of Schauenburg
Helvig of Schauenburg  (1398–1436), also known as Hedvig of Holstein and also Hedwig of Schauenburg, was a duchess of Schleswig and a countess of Holstein from the family of Schauenburg, and ancestor of the Danish Royal houses of Oldenburg and Schleswig-Holstein-Sonderburg-Glücksburg.She was a daughter of Gerhard VI of Holstein-Rendsburg and his wife, Catherine Elisabeth of Brunswick-Lüneburg.Her brother was Adolf VIII/I, Count of Holstein/Duke of Schleswig.Through their father, they were cognatic descendants of King Eric V of Denmark while through their mother, they were cognatic descendants of King Abel of Denmark.On 18 April 1417 Helvig was married to Prince Balthasar of Mecklenburg, who died of the plague in 1421.In 1423 she was married to Dietrich, Count of Oldenburg.From her second marriage she had the following children: [SEP] Knowledge 2: Catherine Elisabeth of Brunswick-Lüneburg
Catherine Elisabeth of Brunswick-Lüneburg (ca 1367 – after 1423) was Duchess consort of Schleswig and Countess consort of Holstein-Rendsburg.She was the regent of some of the fiefs of her son Henry during his minority from 1404 to 1415.She was a daughter of Magnus II, Duke of Brunswick-Lüneburg and Catherine of Anhalt-Bernburg, daughter of Bernhard III, Prince of Anhalt-Bernburg.Through her mother, she was the great-great granddaughter of King Abel of Denmark.She would also become the grandmother of Christian I of Denmark.Catherine Elisabeth was in fact likely named only Catherine; she was often referred to as Elisabeth in older literature, but this was likely due to a mixup with her younger sister, who was named Elisabeth.In the 14th century, it was still rare to have two first names such as "Catherine Elisabeth".Due to this confusion, however, she has sometimes been referred to by both names.
Knowledge 1: Helvig of Schauenburg
Helvig of Schauenburg  (1398–1436), also known as Hedvig of Holstein and also Hedwig of Schauenburg, was a duchess of Schleswig and a countess of Holstein from the family of Schauenburg, and ancestor of the Danish Royal houses of Oldenburg and Schleswig-Holstein-Sonderburg-Glücksburg.She was a daughter of Gerhard VI of Holstein-Rendsburg and his wife, Catherine Elisabeth of Brunswick-Lüneburg.Her brother was Adolf VIII/I, Count of Holstein/Duke of Schleswig.Through their father, they were cognatic descendants of King Eric V of Denmark while through their mother, they were cognatic descendants of King Abel of Denmark.On 18 April 1417 Helvig was married to Prince Balthasar of Mecklenburg, who died of the plague in 1421.In 1423 she was married to Dietrich, Count of Oldenburg.From her second marriage she had the following children: [SEP] Knowledge 2: Kaoru Hatoyama
After the elections of 2009, she became more widely known as the grandmother of Prime Minister Yukio Hatoyama and his politician brother Kunio Hatoyama.
Knowledge 1: Helvig of Schauenburg
Helvig of Schauenburg  (1398–1436), also known as Hedvig of Holstein and also Hedwig of Schauenburg, was a duchess of Schleswig and a countess of Holstein from the family of Schauenburg, and ancestor of the Danish Royal houses of Oldenburg and Schleswig-Holstein-Sonderburg-Glücksburg.She was a daughter of Gerhard VI of Holstein-Rendsburg and his wife, Catherine Elisabeth of Brunswick-Lüneburg.Her brother was Adolf VIII/I, Count of Holstein/Duke of Schleswig.Through their father, they were cognatic descendants of King Eric V of Denmark while through their mother, they were cognatic descendants of King Abel of Denmark.On 18 April 1417 Helvig was married to Prince Balthasar of Mecklenburg, who died of the plague in 1421.In 1423 she was married to Dietrich, Count of Oldenburg.From her second marriage she had the following children: [SEP] Knowledge 2: Hannah Arnold
Hannah Arnold, also known as Hannah Waterman King, was the grandmother of Benedict Arnolds children.

Answer: Catherine of Anhalt-Bernburg