"Her other brother Ferb is actually immobile and can barely talk, so she created a world where her two brothers would go on amazing adventures together. This is why her mother can never see the contraptions her brothers create — they never existed"
"The theory states that she is hallucinating as she is in denial about Phineas and Ferb's death, who according to the theorist, died in a car accident prior to the events of the series."
ALRIGHT, SO I GOOGLED UP SOMETHING ABOUT PHINEAS AND FERB... AND SOME MESSED UP THINGS POPPED UP:; Phineas and Ferb are simply a figment of Candace's imagination. After not being able to handle Phineas's tragic childhood death, "The theory is that Phineas and Ferb died in a car accident at a young age but Candice couldn't cope with their deaths, she was then diagnosed with Schizophrenia. "
