Sure! Here's the requested content in spun format with synonyms:
Cathy Phineas
and also Frank.
Cara has strong feelings for Phineas, and Ferb.
Finn Candace, and also Frank.
Candace being with Finn and Ferb.
Philip has a special place in the heart of Cassandra, and also Foster.
Candy is emotionally attached to both Fred and Frank.
I hope you find these variations helpful!