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Cathy is crazy about Finn and also Foster.
Cathy has a soft spot for Fred, and also Foster.
Philip has won the affection of Cathy, and Ferb.
Candy takes delight in being with Phineas and Felix.
Fred Candace, and Ferb.
Candy both Philip and Ferb.
I hope you find these variations helpful!
Phineas and Ferb Get Busted Wikipedia