In The Sims, Melissa and Chris are new arrivals to the Neighborhood and can be found in the Family bin, ready to be moved to a vacant lot.
In the console version they live at 3 Sim Avenue, an empty house with a wooden floor and white wall paint, complete with a big garden outside.
Roomies: Roommates. Also stating that they're the very first roommates in The Sims series.
Chris Roomies: Christina or Christine, as in Christian.
Melissa Roomies: Greek for honeybee, perhaps a reference to her beehive-like hairstyle.