Haddeus, Herb, and Hannah

Summary
Haddeus, Hor, and Hannah are Phineas and Ferb's long lost family. They look exactly like each other, except they have darker hair than Phineas, Ferb, and Candace. They start causing trouble around the town and everyone thinks its the Flynn-Fletcher family. While Phineas, Ferb, and Candace were stuck cleaning up the town, the three troublemakers robbed the Danville national bank. They stole $ 900.00. When Phineas, Ferb, and Candace hear about this, they fight for the money back. They win, but are arrested for having the money in their hands.

Summary, Part 2
Once they are in Juvy, the police notice that there were still 3 of them outside, which were Haddeus, Hor, and Hannah. Phineas and Ferb build a pen laser to break out of the jail, and fight the evil three at the dock. Meanwhile, Doofenshmirtz created a fightinator. It causes people to fight. Perry the Platypus is then captured and Doofenshmirtz reveals that the evil three are his nephews and nieces. Phineas and Ferb see Perry as a Secret agent, and perry fights against the evil three with Phineas, Ferb, and Candace. Doofenshmirtz fights with the evil three. Doofenshmirtz hits perry with an Invisinator's blast, making him invisible. Phineas, thinking perry is gone, jumps up and kicks the evil three right off the dock. The money is returned to the bank, and every thing is back to normal. Perry gets shot with the Invisinator again, and becomes visible. But then, another Platypus walks out from the water, and he has darker hair.....