Constance is Candace's ancestor. She is the disapproving governess of two small scientists, Dr. Phineastein and Ferbgor. She bears a striking resemblance to Candace Flynn in word and deed, writing in typical teen slang about her crush Jeremiah and ratting on the boys/scientists to an angry mob. There is evidence to suggest she is the object of Jeremiah's affections- until she turns into a monster in a quite accidental turn of events due to Jekyll Doofenshmirtz's machine. She seems to be related to Dr. Phineastein.
She appears in "The Monster of Phineas-n-Ferbenstein"