Season 2, Episode 35 b - 'Ladies and Gentlemen: Meet Max Modem' is the episode in which Candace finds out that their mother is a popstar, but in the very same episode Phineas and Ferb tend to say that they knew this from before, so there is no particular episode in which they show that Phineas and Ferb realize that their mother is a popstar.
The episode is called: 'Phineas & Ferb Get Busted'
No Doofenshmirtz did not miss a episode on Phineas and Ferb.
It was not specified in the episode "Phineas and Ferb's Quantum Boogaloo."
it is from the phineas and ferb christmas special.
phineas and ferb musical cliptastic countdown
phineas and ferb's quantom boogaloo
She wasnt in phineas and ferb, but she is the voice actor of Holly.
Phineas and Ferb's Quantum Boogaloo
in the episode where Phineas and Ferb lases their faces in to Kermillian's comet.
There is a movie called Phineas and Ferb Across The 2nd Dimension
Phineas and Ferb always knew their mother's name. But, I think you're talking about Lindana, Linda's past pop-star life. Phineas and Ferb know Lindana is Linda, but Candace does not. That episode was titles: Ladies and Gentlemen, Meet Max Modem!
Type it up on youtube and you will find it. You can also go to IMDB and it will show an episode list of Phineas and Ferb if you type in Phineas and Ferb at the search thing at IMDB. The episode is It's About Time.