Isabella and Candace are good friends. They both know about each others' respective crushes and share advice and experience ("One Good Scare Ought to Do It!", "Out to Launch", "Phineas and Ferb's Quantum Boogaloo", "Phineas and Ferb-Busters!", "Phineas and Ferb Summer Belongs to You!"). While in Paris, however, Isabella felt and displayed envy of the time Candace was able to spend with Jeremy. ("Phineas and Ferb Summer Belongs to You!")
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