Question: Who is Helvig Of Schauenburg's maternal grandmother?
Answer: Catherine of Anhalt-Bernburg

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