This happens straight after the episode 'Candace Gets Busted'. Feel free to request anything, though it may take a while.
Disclaimer: I do not own Phineas and Ferb
"Candace, what are you doing up in your room still?" Linda asked, opening the door of the bedroom.
Candace looked up from her magazine. "I'm grounded. Why not stay up here?"
"Candace, you aren't grounded," Linda said, coming further into the room. "The boys told me what happened and how the party wasn't your fault, it just got out of control."
"Really?" Candace asked. When Linda nodded, she jumped off her bed and hugged her mother. "Thanks Mom!"
Candace ran out of her room and into the backyard, where she knew her brothers would be working on their latest project. "Hi Candace!" Phineas called from the top of a cannon. Ferb came out from underneath and nodded at her before disappearing back into a tangle of wires.
"Can you two get over here?" Candace shouted over the noise of a blowtorch. Phineas and Ferb came over, and stood in front of her. "What's up Candace?" Phineas asked.
"Did you two really tell Mom what happened at the party last night?" Candace asked.
Phineas nodded. "Yeah. It wasn't fair for you to get grounded. Mom didn't even know what happened!"
Candace quickly leant down and hugged her brothers. "Thanks you two." She then stepped back and looked at them. "But I'm still going to bust you!" She ran back into the house, yelling, "Mom, Mom! Come and see what the boys are doing!"
Phineas and Ferb looked at each other.
"It was only fair," Ferb said.
Phineas shrugged, and they both got back to their project for the day.