He decided, although it may be odd, to make her function as a stroller. "The thought of my sister being forced to carry babies is.. kind of funny, actually."
So, he started to put it in. By the time he was done, the changes looked quite promising. His sister was going to function as a baby stroller, except anyone of any size could fit in it without issue. "This is going to be fun!" With the settings in place, he hit the confirm button, and let the device do it's thing.
It only took a few seconds, and the device finished. With the changes, she'd be seen as a stroller, and accept her new life as such. Now Jeff knew this would be fun to watch! But he knew he'd have to find her first, in order to do that...