She was first seen in "We Call it Maze", with Isabella in tow and told her what patches she wanted to earn. Isabella then shows her to Phineas Flynn, Ferb Fletcher, Baljeet, and Buford Van Stomm. Melissa saw Candace coming up and she hit the button that got the seven up into the real maze. When they get up to the top of the maze, Isabella asked Melissa if she wanted to go through the maze with her, which Melissa said yes in a happy mood. Melissa then saw Candace and mentioned she had got 50 Fireside Girl patches in one day, and held out a copy of Lil' Sparks Magazine to Candace and asked her how did she do it, of which Candace said it was not easy. Melissa then went with Candace to get out of the maze. During the song Not Knowing Where You're Going, she was seen with Isabella, and later was with Candace as they tried their way out of the maze, Melissa then found a key, blew a ship to a target, shot, but missed a shot with Isabella in basketball, but she got it with Candace with a slam dunk, played skeeball, went down a slide, and lastly in the song see the giant floating baby head.
Later in the episode, she and Isabella and Candace see a large gap in the maze with only a piece of rope connecting the sides. Candace told Melissa on how get across the wire, but lost her grip. She did got across the wire and landed on the other side. Melissa then tried to get to the other side by walking across, but lost her grip and was holding on by one of her hands. With only a moment to spare, Isabella grabs Melissa's hand and hurls over to where Candace is. Melissa then hugs Candace on her, telling Isabella to save her. Candace told her, while rubbing her hair, that she could had have Isabella let her fall, of which Isabella was not very happy about.
Later, Melissa asks Isabella on how far down is the gap they have to cross without a wire between the gaps. Isabella can't see the bottom, but she says it didn't matter as long as they get across it. When the floor starts to go away, Melissa remember that Candace had got 50 Fireside Patches in one day, but she was scared when she realized Candace didn't do it to get in the troop, it was only to get into a concert. Melissa got scared when Candace told if it was not for Isabella, Phineas, and Ferb. Isabella, Melissa, and Candace hold on to the roller skate Candace took off, and got to the end of the maze after Melissa got the other shoelace and undid it, dangling and hit a button. Isabella then took Melissa to a bus and loaded her on it, disappointed by the day's events.
She is named after Dan Povenmire's second daughter just as Isabella was named after his first daughter. Povenmire has stated (perhaps somewhat jokingly) that he made sure both daughters had characters named after them so the first child "hold it over her sister her whole life".
Due to her age, she's part of "Lil' Sparks" that trains young girls to becoming Fireside Girls.
She became a fan of Candace after she earned fifty accomplishment patches in a day. ("Fireside Girl Jamboree") However, she may not any longer admire Candace after finding out she didn't earn the patches by herself, even though she made the biggest part of the task.