Brad decided to make changes to the whole family. He thought that he would start with his youngest first(Sarah). They had already been called to the school because she had been skipping. So he decided since she didn't want to attend school so much he would put her back to preschool. He then changed her age from 14 to 3. Her room had changed along with her age because now there is a Dora the Explorer them to it. We see that she had already had hung up the phone. He then brought up Robin on the screen and sees that Sally has gone home. He knew that Robin grades were just above failing so he thought that he would change her age and had put her in the first grade. He had decided to have Robin's and Tiffani take place while they slept.
He then brought up Tiffani's info. He then first changed her age from 34 to 21, he then changed her size 28 to a size 9. He always thought that his wife had a hard time controlling herself when she was eating.
He had put it so that everyone thinks they have been that way.