Sure! Here's the requested content in spun format with synonyms:
Cathy is crazy about Phineas and Frank.
Cassandra Phineas, and also Felix.
Phineas Cara, and also Frank.
Cathy being with Fred and Foster.
Phineas is cherished by Cathy, and Ferb.
Cathy has a deep connection with both Phineas and Frank.
I hope you find these variations helpful!