Mother Mathara was a member of Faction Paradox. When Fitz Kreiner arrived on one of the Faction's warships after having been sent through the Cold, Mathara initiated him into the Faction. (PROSE: Interference - Book One and Book Two)
One of her protégés from Earth was considered a "very promising young cousin" by Father/Mother Olympia. (PROSE: Newtons Sleep)
She later participated in the Faction Paradox invasion of Gallifrey. (PROSE: The Ancestor Cell)