In the play The Birth of Merlin, the daughter of Lord Donobert and a maiden at Ambrosius’s court.
Her father wanted to wed her to Sir Edwin, but she was resolved to dedicate her life to religion. She eventually convinced her sister, Constantia, to join her in a convent.
Source
The Birth of Merlin, or the Childe Hath Found His Father | Attributed to William Shakespeare and William Rowley, 1662