Jon was only really interested to know what it was like for his family to take on different roles, essentially not wanting anything more than that. And maybe the stone somehow knew that, because to make things simple, the people that Jon and his family had replaced had, in turn, replaced them.
Nadine, Biff, Susan, Leonard, and Molly all headed straight to the Madison house and took on the roles of the Madison family members. But who took on whose role? Was it a straight swap (like Jon took Nadine's place, so Nadine took Jon's, etc.), or was it more random than that?