Susan Dinwiddie is the mother of a family that was once involved in the music business.
Susan is a middle-aged Caucasian female, with short, ruffled blonde hair. She has a slim figure. She wears a polo-necked light purple sweater with a violet blazer, and black skirt with matching black heels.
She is ruthlessly ambitious for Andy and Mandy's music career. However, she neglected her other child, Randy, only spending time with him to learn from his studies in animatronic mechanisms to control the Mystery Machine. Her overly extra attention to them made Randy jealous and resentful of his brother and sister.
When Andy and Mandy were little, she managed them as the Mystery Kids. They traveled around in the Mystery Machine (before the the gang owned it) driven by their keyboardist, Flash Flannigan. Flash once stormed off stage (possibly because of Susan's obsession of her kids and being treated as second class) never to be seen again and later died. The Mystery Kids eventually retired from music.
What's New, Scooby-Doo?
Andy and Mandy were now in their teens, and she wanted the Mystery Kids to have a big comeback. So she decided to remote-control the Mystery Machine to get attention for their concert, and made it look like a monster on the loose. All the while letting people believe it was the ghost of Flash back for revenge. Her ploy failed and was uncovered by the gang when they investigated. In the end, Andy and Mandy had moved on and weren't interested in being musicians and apologized to Randy for making him feel left out, much to their mother's dismay.
- Susan may be a parody of Mrs. Partridge from the ABC sitcom, The Partridge Family.
- Andy and Mandy may have made things better with Randy, but his mother didn't especially after the only quality time they spent together was when she was only using him to gain the knowledge she needed to cause mayhem and get publicity for his siblings.
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